实用英语写作技巧
单元目录第一单元 段落简介
第二单元 主题句简介
第三单元 如何写好主题句
第四单元 如何写推展句
第五单元如何写结论句
第六单元 如何写好一个段落（Ⅰ）
第七单元如何写好一个段落（Ⅱ）
第八单元 推展段落方法之一——事实与数据法
第九单元 推展段落方法之二——叙述法
第十单元 推展段落方法之三——描述法
第十一单元 推展段落方法之四
第十二单元 组织段落方法——时间顺序法和空间顺序法
第十三单元 推展段落方法之五——举例法
第十四单元 推展段落方法之六
第十五单元 推展段落方法之七——下定义法
第十六单元 推展段落方法之八——分类法
第十七单元 推展段落方法之九——因果法（Ⅰ）
第十八单元 推展段落方法之九——因果法（Ⅱ）
第十九单元 组织段落方法——重要性和熟悉度顺序
第二十单元 推展段落方法——混合方法
第二十一单元 从段落到篇章
第二十二单元 篇章的统一性、支撑性、连贯性和一致性
第二十三单元 如何用举例法推展篇章
第二十四单元 如何用比较与对照法推展篇章
第二十五单元 如何用定义与分类法推展篇章
第二十六单元 如何用过程分析法推展篇章
第二十七单元 如何用因果法推展篇章
第二十八单元 情景作文Situational Composition
第二十九单元 主题句作文Topic Sentence Composition
第三十单元 关键词作文Key Words Composition
第三十一单元 给出题目作文Title-Given Composition
第三十二单元 图表作文Writing a Composition According
第三十三单元 英文书信写作English Letter Writing
第三十四单元 转换词语Transitional Words and Phrases
第三十五单元 总复习Revision Exercises
第一单元 段落简介
1．1段落
段落是构成文章的一组句子。段落必须表达完整的意思：或描写事物（describe something），或争论某事（argue about something），或对某事提出疑问（question something），或要求什么（demand something），或给事物下定义（define something），或驳斥某观点（reject something）。
1．2典型段落的构成
一个典型的段落通常由三部分组成：（1）主题句（the topic sentence）；（2）说明或支持主题的推展句（ supporting sentences）；（3）结论句（the concluding sentence）（有些段落没有该部分）。
示范段落1-1
We all know that cigarette smoking is a dangerous habit because it causes health problems． Doctors say it can be a direct cause of cancer of the lungs and throat and can also contribute to cancer of other organs． In addition， it can bring about other health problems such as heart and lung diseases． It is clearly identified as one of the chief causes of death in our society．
1．3示范段落分析
这是一个典型的段落，可概括提纲如下：
主题句： We all know that cigarette smoking is a dangerous habit，because it causes health problems．
推展句： 1． Doctors say it can be a direc cause of cancer of the lungs and throat and can also contribute to cancer of other organs．
2． It can bring about other health problems such as heart and lung diseases．
结论句： It is clearly identified as one of the chief causes of death in our society．
从以上提纲可见，主题句提出了一个问题： What kind of health problems does cigarette smoking cause？随后的两个推展句回答了这个问题，结论句总结了推展句并再一次强调主题句。
Exercise 1-1
Directions： Read the following paragraphs and find out the topic sentence， the supporting details and the concluding sentence， if there is one．
（1）
The need for wildlife protection is greater now than ever before．About a thousand species of animals are in danger of extinction,，and the rate at which they are being destroyed has increased． With mammals， for instance， the rate of extinction is now about one species every year； from A． D． 1 to 1800， the ratewas about one species every fifty years． Everywhere， men are trying o solve the problem of preserving wildlife while caring at the same time for the world’s growing population．
Topic Sentence：____________________________________________
______________________________________________________________
Details： 1．________________________________________________
______________________________________________________________
2．_______________________________________________________
______________________________________________________________
Concluding Sentence：________________________________________
______________________________________________________________
（2）
The Americans and the British not only speak the same language but also share a large number of social customs．For example， in both America and England， people shake hands when they meet each other for the first time． Also， most English men will open a door for a woman or offer their seat to a woman， and so will most Americans． Promptness is important both in England and in America． That is， if a dinner invitation is for 7 o’clock， the dinner guest either arrives close to that time or calls up to explain his delay．
Topic Sentence：____________________________________________
______________________________________________________________
Details： 1．______________________________________________
______________________________________________________________
2．_______________________________________________________
______________________________________________________________
3．________________________________________________________
______________________________________________________________
Concluding Sentence：________________________________________
______________________________________________________________
（3）
Birds use many different materials to build nests．Some birds use bits of grass． The tailor-bird of Africa and India uses grass to sew leaves together． Other birds find twigs and pebbles useful．
Topic Sentence：_____________________________________________
______________________________________________________________
Details： 1．_____________________________________________
______________________________________________________________
2．______________________________________________________
______________________________________________________________
3．______________________________________________________
______________________________________________________________
Concluding Sentence：_______________________________________
______________________________________________________________
第二单元 主题句简介
2．1主题句作者的首要任务是让读者知道所写段落要谈的是什么，这就是每段的主题句的作用。因此主题句应该阐明段落的主要思想，所有支持主题句的细节和描述都与这一主要思想有关。
2．2主题句的形式
主题句通常有以下三种形式：
1）肯定句（Affirmative Sentence）
Example： The need for wildlife protection is greater now than ever before．
2）反诘句（Rhetorical Sentence）
Example： How do you think people will solve the problem of wildlife protection？
3）不完整句（Fragments）
Example： And the workingman？
初学者最好使用肯定句作为主题句。
2．3主题句的位置
主题句出现的位置有以下四种情况：
1）段首（At the beginning）
主题句经常居于段首，以便读者浏览主题句就可掌握文章的概要。这个位置适用于写提供信息或解释观点的段落。
2）段末（At the end）
用推理方法展开段落时，主题句往往位于句末。
3）段中（In the middle）
有时为了使段落多样化，主题句也可以居于段中。
4）隐含（Implied）
有时候，尤其在写叙述性或描写性段落时，当所有的细节都围绕着一个显而易见的主题时可以不用主题句。
Exercise 2-1
Directions： Read the following paragraphs and identify the topic sentence． If it is implied， summarize it yourself．
（1）
But no matter what it is called， all polyester has certain good points． It does not wrinkle easily． It dries quickly after it is washed． It holds its shape． It is strong and keeps its colors well．
Topic Sentence：____________________________________________
Position：________________
（2）
Black is the colour of mourning． Red symbolizes danger，violence，or bloodshed． If you are afraid， you are yellow． None of these sayings is true outside the English speaking world． In China and Korea， white is the color of mourning． In Russia red stands for beauty and life． In Italy and Germany you are yellow with anger，not with fear．
Topic Sentence：_____________________________________________
Position：__________________
（3）
Our chief source of fresh water is rainfall that collects in lakes，rivers， and reservoirs． Recently， however， we have discovered anew source， aquifers， which are rock formations containing water．Even under deserts， vast aquifers may be waiting to be tapped．Companies drilling for oil in the Middle East have sometimes struck aquifers， which provide unexpected water supplies for arid regions．
Topic Sentence：____________________________________________
Position：_____________
（4）
Suppose you’re playing a game． You make a silly mistake and lose． Do you become angry？ Or can you laugh at yourself and hope to do better next time？ Suppose you are at a special dinner．You accidentally spill some food．Why keep worrying about how clumsy you look？Why not laugh it off and enjoy yourself anyway？If you can， it’s good sign you've really grown up．
Topic Sentence：____________________________________________
Position：____________
（5）
Young men sometimes bring edelweiss back for their girlfriends． The girls think of the flowers as a proof of true love．Mountain climbers， guides， and hunters pick edelweiss too．They wear it on their hats． To them it is a sign of courage and daring．
Topic Sentence：____________________________________________
Position：____________
第三单元 如何写好主题句
3．1关于写主题句的建议1）要写合乎语法的句子
Example 1： Two causes of the American Civil War．
这个句子是个不完整的句子，不合乎语法，因此不能用作主题句。
Example 2： There were two causes that led to the American Civil War．
重写后的句子合乎语法，是个较好的主题句。
2）要使用限写词限定主题
为了正确表达观点，好的主题句经常使用关键词或词组，即限制词（controllers）限制这一观点。
Example 3： Air travel is more convenient than train for at least three reasons．
从上例主题句我们得知作者将要写“air travel”（ topic），他将要把 “train”（ aspect）和“ air travel”作比较，并且陈述“reasons”。由此可见，作者在“aspect”（方面）和“reason”（原因）两方面限制他的主题。
3）要注意主题的可写性
所定的主题不能太笼统，也不能太具体。
Example 4： In Hemingway's story “Soldier’s Home”，Krebs tells his mother that he wants no part of God's Kingdom．
这个句子太具体以至于无东西可写，无法展开段落。
Example 5： In Hemingway's story “Soldier’s Home”， Kreb is a lonely， cynical veteran．
这个句子可作为主题句，因为可以围绕“lonely，cynical”展开段落。
Example 6： Let me tell you something about overpopulation．
这个句子太笼统，作为一个段落的主题太大，难于驾驭。
Example 7： Why has the world population been increasing sorapidly in the last decades？
这个句子是个较好的主题句，作者用“the reasons for overpopulation in the last decades”，从“原因”（cause）和“时间”（time）两方面限制了主题，能在一个段落内论述。
Exercise 3-1
Directions： Identify the areas which limit the topic sentences．
3．1．1 Soccer has become increasingly popular in the U． S． in the last ten years．
Topic：_____________
Limitations：________________________________________________
3．1．2 Pollution has caused three major problems in the last decades．
Topic：______________
Limitations：________________________________________________
3．1．3There are two kinds of memory： short-term and long-term．
Topic：____________
Limitations：________________________________________________
3．1．4 Women are playing an increasingly important part in society today．
Topic：____________
Limitations：________________________________________________
3．1．5 Women are paid less for equal work than men in some companies．
Topic：____________
Limitations：________________________________________________
Exercise 3-2
Directions： Write two topic sentences for each of the topics，limiting the topic in different ways．
3． 2． 1 Topic： the study of English
Topic Sentence 1：__________________________________________
Topic Sentence 2：___________________________________________
3．2．2 Topic： college students today
Topic Sentence 1：__________________________________________
Topic Sentence 2：__________________________________________
3．2．3 Topic： women in China
Topic Sentence 1：__________________________________________
Topic Sentence 2：__________________________________________
3．2．4 Topic：crime
Topic Sentence 1：__________________________________________
Topic Sentence 2：__________________________________________
Exercise 3-3
Directions： Read the following paragraphs and supply the missing topic sentence．
（1）
________________________________________________________________________________________________________________________
Iceland’s flag， for instance， stands for features of the land．Red for the fire of Iceland’s volcanoes． White is for ice． Blue is for the mountains． On India’s flag， the blue wheel stands for peace and progress． The white stripe behind it is for truth． The black stripe on the flag of Malawi stands for the Negro people of that African land． The red stripe represents the blood they shed to free themselves from foreign rule．
（2）
________________________________________________________________________________________________________________________
The one most people are familiar with is the“desk dictionary”，sometimes refered to as general-purpose dictionary． Another kind is the pronouncing dictionary， which is concerned with a word's pronunciation more than with its meaning． A third type is the bilingual dictionary， which lists the words in one language and attempts to give equivalent meaning in another language． Other types include technical dictionaries， special purpose dictionaries，and scholarly dictionaries．
第四单元 如何写推展句
第四单元 如何写推展句4．1段落的推展
在前几单元中，我们谈到写段落的第一个步骤是写主题句。作者要对主题句在某些方面加以限制。第二个步骤将是写推展句。例如你要陈述你选择某院校的理由，第一步，写出主题句：
There are two main reasons why I have decided to attend Bingston University next year．
第二步，以数个理由推展你的主题：
示范段落4-1
① There are two main reasons why I have decided to attend Bingston University next year．② First of all， there is the question of money：Bingstonv's tuition is reasonable and I don’t even have to pay it all at once．③ This is very important， since my father is not a rich man．④ With Bingston's “deferred payment plan，” my father will be able to pay my tuition without too much difficulty．⑤The second resaon is the fine education which I feed will receive there in agriculture， my chosen field．⑥ It is a well-known fact that Bingston hires only the finest professors in its Agriculture Department．⑦ Moreover， the university reqires all agricultural students to get practical experience by working on farms in the areawhile they are still going to school．
4．2示范段落分析
细节： two main reasons：
理由 1—financial consideration②
a． reasonable tuition③
b． deferred payment plan④
理由 2—quality of education⑤
a． fine teachers③
b． practical experience⑦
在两个主要理由之下，作者用更小的细节支持它们。
由此可见，段落的推展依赖于支持主题句的细节（details）。推展段落的方法很多。通常每个段落以一种方法为“支配方法”（ the dominant method），必要时，可运用其它一种或数种方法作为“辅助方法”（ the supporting method）。上面的示范段落使用因果法（cause-and-effect）作为支配方法，分类法（division and classification）作为辅助方法。作者还运用了“重要性排列顺序”（the order of importance）作为安排细节、组织段落的手段。我们将在以下各单元逐个讨论这些方法。
Exercise4-1
Directions： Read the following paragraphs and find out what details the authors use to support their topic sentences．
（1）
Warm water freezes more quickly than cold． Sir Francis Bacon stated that almost four hundred years ago． But few people believedhim—till 1970． In that year， Canadian scientist George Kell proved the English scholar right． Dr． Kell filled an open pail with cold water． He filled another with warm water． He exposed both to the same low temperature． The warm water froze first．
Topic Sentence：____________________________________________
Details：1．________________________________________________
2．________________________________________________
（2）
There is a relationship between your blood type and your nationality． Among Europeans and people of European ancestry，about 42 percent have type A while 45 percent have type O．The rarest is type B． Other races have different percentages．For example， some American Indian groups have nearly 100 percent type O．
Topic Sentence：____________________________________________
Details：1．________________________________________________
2．________________________________________________
（3）
Although thousands of people have been killed by sudden eruptions， volcanoes also benefit man， Tin， tungsten， gold and other metals have been brought closer to the earth’s surface．Chemicals in the ash have enriched farmland． When solid， lava is agood building material． And in Italy， steam from active volcanoes supplies heat and power to surrounding areas．
Topic Sentence：____________________________________________
Details：1．_______________________________________________
2．_______________________________________________
3．_______________________________________________
4．_______________________________________________
（4）
The Women’s Movement has had several effects on the English language． It has created Ms， a title for women comparable to the title Mr． for men． The creator of the new title objected to the title Miss and Mrs． once given to women because these titles violated a woman's privacy by indicating her marital status． The use of Ms．now permits women to enjoy the same privacy that men have enjoyed with the use of Mr． Second， the Movement has changed the ending of many compound words from-man to-person．For instance， the word “chairman” has been replaced in many organization with the word “chairperson”， and the word“salesman”has become salesperson． Feminists insist that the substitution of-person for-man makes the position more suitable for members of either sex． Third， the Movement is responsible for new terms．One example is male chauvinist pig， a term applied to a man who refuses to recognize the equality of women． Another example is female chauvinist sow， a phrase used to describe a female who believes that she is superior to males． The most profound effect the Movementhas had on the language is on the third person singular pronoun．Thirty years ago most English instructors forced their students to se he， him， and his for the third person singular when the sex of the person was not known． Thus， students were taught to say，“Everyone has his books”．Today many English teachers permit students to follow the feminist lead and use the masculine and feminine pronouns together． Therefore， constructions such as his or her books are common． Although the Women's Movement may not have yet achieved all of its goals， it has made a mark on the English language．
Topic Sentence：___________________________________________
Details：1．______________________________________________
2．______________________________________________
3．______________________________________________
4．______________________________________________
第五单元如何写结论句
第五单元如何写结论句5．1结论句
第一单元曾提到，段落由三个部分组成，最后一部分就是结论句（ the concluding sentence）。结论句通常与主题句一样包含有段落的中心思想，然而所用措辞与主题句不同。
在示范段落 1-1，主题句是： We all know that cigarette smoking is a dangerous habit because it causes health problems．
结论句是： It is clearly identified as one of the chief causes of death in our society．
5．2关于写结论句的建议
1）把握主题句的关键词
例如在关于“cigarette smoking”的示范段落 1-1中，中心思想是“the health problems caused by cigarette smoking，关键词是“health problems”。
2）总结细节，回答主题句中隐含的问题。
在上述示范段落中，隐含的问题是“What are the health problems caused by cigarette smoking？”结论句作出的回答是 It is identified as one of the chief cause of death in our society．
3）用不同的措辞表达同一中心思想。
在上述段落中，主题句的关键词是“health problems”，而在结论句中，关键词是“causes of death”。
示范段落5-1
Our neighborhood has been greatly changed． When I last visited there， about half the homes had been torn down to make way for a superhighway． The remaining buildings were plastered with billboards and surrounded by traffic signs and litter． Now the whole neighborhood has become dirty， noisy and full of cars．
5．3示范段落分析
主题句： Our neighborhood has been changed．
主题句关键词： changed
主题句隐含的问题：“How has the neighborhood changed？
细节： 1． a superhighway built—noisy and full of cars
2． full of billboards， traffic signs and litter—dirty
结论句： Now the whole neighborhood has become dirty， noisy andfull of cars．
结论句关键词： dirty，noisy and full of cars
结论句总结了细节并回答了主题句提出的问题。
Exercise 5-1
Directions：Read the following paragraph．Find out the topic sentence and the concluding sentence， and rearrange the details so that the paragraph will make sense．
① In less than three years the farm had gone to pieces．②All the windows had been broken out of the big two-story farm house．③In the front of the house the grass was about three feet tall andthe barn yard was full of weeds instead of pigs squealing to be fed．④There were no more cows to milk or horses to ride．⑤My grandmother's farm has a lot of enjoyable memories for me，but after she died， I left home to join the army and when I returned，I was disappointed at the changes that had taken place．⑥ Paint was peeling off the house and the porch roof was sagging．⑦ Lively as the place had been before my grandmother died， it seemed to have died with her now．⑧This farm had once been lively with the noise of a tractor plowing the land and a dog barking whenever someone came up to the house．
Topic Sentence：________Supporting Details：________
Concluding Sentence：_________
Exercise 5-2
Directions： Read the following paragraphs and underline the topic sentence of each． Then write your own concluding sentence to complete each paragraph．
（1）
Pollution has caused three major problems in the last decades．First， with the development of industry， more and more factories have been built and have sent out smoke and poisonous gases．Thus the air is polluted． The increasing number of cars adds to the air pollution． Second， farmers use chemical fertilizers to increase production and insecticide to kill insects． When rain flows with these poisonous chemicals to rivers， water is polluted． A third formof pollution， noise， is becoming more and more serious． Very loud noises can make people sick， and even drive them mad．
____________________________________________________________________________________________________________________________
（2）
There are three important findings from studies concerned with notetaking． First，notetaking does not interfere with listening and comprehension； in fact， it helps you listen． Second， students who study their lecture notes remember one and a half times more after six weeks than students who do not review． Third， students who take no notes， or do not study their notes， forget approximately 80percent of the lecture by the end of two weeks．From these findings we can conclude that students who take enough notes and then study them， both directly after the lecture and several additional times before an examination， stand a good chance of remembering between90 and 100％ of the material！_______________________________________
____________________________________________________________________________________________________________________________
第六单元 如何写好一个段落（Ⅰ）
第六单元 如何写好一个段落（Ⅰ）6．1段落的特征
一个好的段落应该具有以下三个特征：1）完整性（completeness）； 2）统一性（unity）； 3）连贯性（coherence）。
6．2完整性
段落的完整性指的是段落得以充分展开。作者一俟写好主题句，就应该用细节进行推展，细节越充足越好。例如，你认为“Riding motorcycles is dangerous”，你就应该用你所知道的事实证明这一观点是正确的。你可以使用数字（statistics），列举例子（example），进行描绘（descriptions）等等。
示范段落6-1
Ever since the time of the Greeks， drama has played an important role in man's lives． The Greek tragedies and come dies were a central part of the citizens' lives in ancient Greece． During the Middle Ages， Bible stories were acted out in churches，and wandering companies of players performed in the streets． In modern times， drama is brought directly into people's homes through the magic of television．
6．3示范段落分析
主题句： Ever since the time of the Greeks， drama has played animportant role in man's lives．
细节：1． ancient Greece
2． the Middle Ages
3． modern times
作者根据各个不同历史时期提供细节，举例说明戏剧的重要性。
6．4 统一性
一个好的段落应该具有统一性。统一性就是一个中心思想统领整个段落。每个细节都应支持主题句，不应有无关的细节。为了支持主题，要尽可能多地提供细节，但又要避免滥用细节。
读下面段落，然后找出毛病。
① Innovations， whether practical or aesthetic， are often resisted by the general population．② When the early experiments in the field of aviation began their work， there were many who said，“If God had wanted man to fly， he would have given him wings．③The Wright brothers made the first powered flights in a heavier-than-air craft in 1903 at Kitty Hawk， North Carolina．④Even today there are many who strongly object to modern art and music as being nothing more than “splashes of paint and honking horns．”⑤The painter Picasso's well-known masterpiece “The Three Musicians” is done primarily in blues and browns．
6．5段落分析
主题句： Innovations， whether practical or aesthetic， are often resisted by the general population．
推展细节：1． People's objection to the early experiments in the field of aviation．
2． People's objection to modern art and music．
无关细节：1． The Wright brothers' experiment in flight．
2．Picasso's painting．
显然这不是个好的段落，因为并非所有的推展句都支持主题句。应该把无关的细节删去。下图是一个有统一性的段落的结构图。
Exercise 6-1
Directions： In the folowing sentence grouping， circle the letter in front of any detail that does not support the topic sentence．
Topic Sentence：My main satisfaction in life comes from the people who are part of my life．
Supporting Details：
a． For me a day is good or bad depending on whether or not I havegooten along well with my associates．
b． I am not at all affected by the weather the way some people are．
c． For instance， my father judges his day by whether or not the skyis blue．
d． On a rainy day he is always in a bad mood．
e． What counts for me is to feel human warmth and friendship．
f． My favourite entertainment is to be with one or two intimate friends， sitting in front of a fireplace and sharing intimate recollections．
Exercise 6-2
Directions： Read the following paragraph and identify the irrelevant sentences．
① Different people spend their weekends in different ways．②Some enjoy going to the mountains to hike， ski or just relax．③Water skiing is much more difficult than snow skiing．④Others prefer going to the beach to enjoy the seashore activities and to get a suntan．⑤ Some of these people work very hard during the week；others have rather relaxing jobs．⑥ Still others like to relax by staying home and reading a good book．
Topic Sentence：________
Irrelevant Sentences：________________
Exercise 6-3
Directions： List at least five details that might used to develop thegiven topic sentence．
Topic sentence： Day dreaming has always been my favourite．
Details：1．_______________________________________________
2．_______________________________________________
3．_______________________________________________
4．_______________________________________________
5．_______________________________________________
第七单元 如何写好一个段落（Ⅱ）
第七单元如何写好一个段落（Ⅱ）7．1连贯性
段落的连贯性指的是段落的句子以清晰、符合逻辑的顺序（clear， logical sequence）连接。连贯性使读者能够找出每个观点之间的联系以及这些观点与主题句的联系。
7．2关于如何取得连贯性的建议
1）使用同一时态
如果随意而毫无理由地改变时态（tenses），那么不管作者连句的技巧多么高超，段落也不可能取得连贯性。在写作时，可以使用现在时（ present tense）或过去时（past tense）。选用哪一种取决于作者处理材料的方式。
2）使用某种逻辑顺序
常用的逻辑顺序有： 1）时间顺序（time order）； 2）空间顺序（space order）（见第12单元）； 3）重要性顺序（order of importance）和 4）熟悉度顺序（order of familiarity）（见第 19单元）。
3）使用连接成分
使用某些连接词和短语（connective word Sand phrases），重复某些关键词（repetition of certain key words），可以大大增加段落的连贯性。某些连接词、短语和关键词可以起粘着物（adhesives）的作用，把各部分连接起来，使句子间的关系更加清楚。连接成分主要有以下三种：
a．连接词语（linking expressions）（见第34单元）
b．代词（pronouns）
代词用于提醒读者注意其先行词，以此把有关的部分连接起来。
c．重复关键词语（repetition of key words）
示范段落7．1
① Until recently daydreaming was viewed as a waste of time．② Or it was considered an unhealthy escape from real life and its duties．③ But now some people are taking a fresh look at daydreaming．④ And it may be that more people are suffering from a lack of daydreaming than are suffering from too much of it．
7．3示范段落分析
顺序：熟悉度和对比关系
连接词语：①“until recently”②“or”③“but”④“and”⑤“then”
代词：① daydreaming—②it—④ it（the second one）
重复关键词：①daydreaming—③daydreaming
④daydreaming
Exercise 7-1
Directions： Arrange the following sentences into a paragraph，using the coherence devices as the hints．
① Clearly， in agriculture and industry， the progress of a country depends on the busy hands of its working people．
② Finally， the establishment of efficient transportation and communication systems， essential services in a modernizing economy， relies heavily on a lab our force of expert craftsmen who take pride in their manual skills．
③ And of course the manufactures as well as the maintenance of machines of all kinds demands a large number of trained mechanics and technicians．
④ To begin with， ploughing fields，planting and harvesting crops， and raising livestock are all important to development and all require people who work with their hands．
⑤ Secondly， mining natural resources， building roads and bridges， and constructing dams for irrigation and electrical power are also important to development and also require people who know how to use their hands skillfully．
⑥ Manual lab our is one of the principal development resources in any industralizing country， as the following examples demonstrate．
Topic Sentence：____________
Details：___________________
Concluding Sentence：____________
Exercise 7-2
Directions： In the following paragraph， find all the words that help the reader move smoothly from one detail to another．write these words in the blanks to the right．
To prepare a nutritious breakfast of cereal and milk you need tofollow only a few simple directions． First， acquire the necessary ingredients and materials： dry cereal of your choice， milk， sugar，fruit， a cereal bowl and a soup spoon． Second， pour the cereal into the bowl until the bowl is half full． Next ，cut up the fruit and arrange it on top of the cereal； then sprinkle sugar over the fruit，if desired． Once you have layered the cereal and fruit in the bowl，you are ready for the milk． Now， pour enough milk into the bowl to just barely cover the cereal and fruit． At last， your breakfast is ready；pick up your spoon and dig in！
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
第八单元 推展段落方法之一——事实与数据法
第八单元 推展段落方法之一——事实与数据法在第四单元，我们曾提到推展段落的方法有多种。从这一单元开始，我们将逐个介绍这些方法。
8．1事实与数据法
事实（a fact）是可以客观证实的事情。例如：“The sunrises in the east．”是个事实。“Oil and water do not mix．”也是个事实。两者都可以通过实验证明是真实的。但是“Eating carrots improves eyesight．”也许是真实也许是不真实的。这不是个事实，是一种看法（opinion）。数据（a statistic）是一个数字事实（a numeral fact），用于给某一主题提供有意义的信息。例如：
There are twenty－five students in the class．”是一个数据。
示范段落8－1
The term population explosion is usually applied to the rapid growth of population over the last three centuries．In the two hundred years from 1650 to 1850，world population doubled and reached its first billion．In the next eighty years，it doubled again，and by 1975，it had doubled once more to a total of 4 billion．By the year 2000，it is estimated that it will exceed 6 billion and possibly approach 7 billion unless there is a major reduction in birth rates or amajor increase in death rates．
8．2示范段落分析
主题句：The term population explosion is usually applied to the rapid growth of population over the last three centuries．
提供信息：
数据1：1650-1850；double，reach 1 billion
数据2：1850－1930；double again，reach 2 billion
数据3：1930－1975；double again，reach 4 billion
数据4：1975－2000；exceed 6 billion，approach 7 billion
示范段落8-2
A snake is a strange animal．It walks on its ribs and it smells with its tongue．Since its teeth are sharp like needles and not good for chewing，it swallows its food whole．
8．3示范段落分析
主题句：A snake is a strange animal．
事实1：walks with its ribs and smells with its tongue
事实2：swallows its food whole
8．4关于如何写事实与数据段落的建议
1）不要把事实与看法混为一谈
事实是真实的，因为它们已被证据证实。然而看法只是人们的主观想法，不一定真实。因此，记住用事实而不是用看法支持你的观点。
2）不要使用不相关的数据
如果你为了增加观点的可信度而使用不相关的数据，即使这些数据是真实的，也会引起误解。
Exercise 8-1
Directions：Write a paragraph with statistics as supporting details，using the given topic sentence and statistics．
Statistic：blood pressure before the exam—115／55
Statistic：at the end of the exam—155／115
Statistic：ten minutes after the exam—150／110
Exams apparently have a marked effect on the blood pressure of the students taking them．___________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
Exercise 8-2
Directions：Write a paragraph with facts as supporting details using the given topic sentence and facts．
Fact：William is the second most common boy's name used in English（the first being John）
Fact：History is full of Williams．
a．William of Nor many—conquerer of England in 1066
b．William Shakespeare—writer
c．William Cody—a hero of the Wild West
Is your name William？If so， you have company．____________
______________________________________________________________
______________________________________________________________
______________________________________________________________
第九单元 推展段落方法之二——叙述法
第九单元 推展段落方法之二——叙述法9．1叙述法
叙述法（narration）回答了“发生了什么”（what happened）这一问题。叙述经常用于讲述一系列事件。这种方法常用作小说（fiction）、传记（biographs）的支配方法，也可用作其他各种文体的辅助方法。例如，轶事（anecdotes）、寓言（fables）等都是用叙述形式阐述某一观点。
示范段落9－1
I was seven years old when I first became aware of the terrible power of guilt．For piling our toys into the toy box，Mother had rewarded my brother and me with five shiny pennies each．If I had ten pennies instead of just five，I could have bought a ginger bread man with raisin eyes and sugar－frosted hair．The image danced in my head all day，until，finally，I crept into my brother's room and stole his five pennies．The next morning，as my brother and I were dressing to go to school，I had all ten pennies in the pocket of my coat，cramming one of my father's handkerchiefs on top of them．As my brother and I lined up in front of Mother to be kissed goodbye，she looked at my bulging pocket with amazement．“What on earth do you have in your pocket？she asked．“It's nothing，”I said，as offhandedly as I could．“It's nothing at all．”Bewildered，but toobusy to investigate any further，Mother kissed me goodbye I ran out the door and down our gravel path as fast as my feet could carry me．But the farther from home I got，the more miserable I became．The shiny pennies in my pocket felt oppressively like one－ton boulders．And I was haunted by the idea that I had become a thief．Forgotten was the gingerbread man，for whose sake I had stolen my brother's pennies Finally，unable to bear my horrible feeling of guilt，I ran back home to blurt out my crime to my mother．
9．2示范段落分析
在上面段落中，作者在主题句中阐述了他的观点：I was seven years old when I first became aware of the terrible power of guilt．然后用一件轶事作为支持这一观点的细节，叙述发生了什么事，并说明了他的观点。
9．3关于如何写叙述段落的建议
1）只着重叙述有意义的事件和经历
尽量避免日常琐事和无聊事，只使用那些有助于阐明你的观点的事件和经历。
2）保持始终如一的着眼点
不管叙述是以第一人称或第三人称进行，都要尽量使语言从叙述者的着眼点（point of view）反映叙述者的见解和意向。
3）运用细节
写叙述段落时要运用细节，使人物栩栩如生，并在读者的想象中唤起事件发生的那种环境气氛。在描绘人物时也使用细节，使人物血肉丰满，形象生动。
4）使用时间顺序
叙述几乎总是使用时间顺序法来组织细节。（第12单元将讨论时间顺序法）
Exercise 9-1
Directions：Write a paragraph of narration using the given topic sentence．
Not knowing a language well can sometimes be embarrassing．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Exercise 9－2
Directions：Write a paragraph of narration，telling about one of your memorable trip．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
第十单元 推展段落方法之三——描述法
第十单元 推展段落方法之三——描述法10．1描述法
叙述讲述发生了什么事情，描述（description）则向读者描绘某事物的样子、声音、味道等等。作者可以通过外表、行动或变化用语言描绘一个人，一个物体，一个地方或一个场面。
示范段落10－1
A tsunami is a great wave or series of waves．It extends from the surface to the sea floor and moves the entire vertical section of ocean through which it speeds．The greater the ocean depth，the faster the tsunami travels．Speeds of up to 600 mph have been reached．Toward land it slows down as the bottom of the wave drags on the seabed；its crest rises from fifty to a hundred feet or more．
10．2示范段落分析
主题句：A tsunami is a great wave or series of waves．
细节1：extention
细节2：speed（statistics used）
细节3：height（statistics used）
在上面段落中，作者用细节（包括数据）描述了海啸的宽度（extention）、速度（speed）和高度（height），从而告诉读者海啸是什么样子。
示范段落10－2
The kitchen was in a mess．Along the left wall were the counter and sink covered with dirty dishes and garbage．On the far wall the washing machine groaned under a load of filthy clothes．Right next to the door where I was standing，on my right，I saw at able cluttered with old newspapers，an overturned catsup bottle，and a wet，half－eaten hot dog．At the far end of the right wall the refrigerator stood with the door ajar and milk dripping down from the top shelf．It was the messiest kitchen I had ever seen．
10．3示范段落分析
主题句：The kitchen was in a mess．
细节1：Along the left wall—counter and sink
细节2：On the far wall—washing machine
细节3：Right next to the door，on my right—table
细节4：At the far end of the right wall—refrigerator
结论句：It was the messiest kitchen I had ever seen．
10．4关于如何写描述段落的建议
1）主题句给读者一个深刻的印象
写一段好的描述段落要注意两个方面：首先给读者一个深刻的印象（a dominant impression），然后运用充分的细节（aptdetails）。这种深刻的印象必须首先吸引读者，因此不要在主题句中用太琐碎的东西冲淡这一印象。
比较下面两个主题句：
a．The kitchen is in a mess．
b．The kitchen is a place where the hostess does almost all the housework and as a consequence it is not always attractive and neat．
显然，前一句主题句比后一句更吸引读者，因为它能给人以更深刻的印象。
2）提供充足的细节
具体和生动的细节是成功的描述所不可缺少的。在示范段落10-1中，作者通过海啸外表的生动细节以及速度和高度的具体数据描述海啸。在示范段落10－2中，在主题句后，作者提供细节描绘厨房是怎样的乱七八糟。记住不要提供无用的细节使读者失望。
3）使用空间顺序法（space order）组织段落
好的描述还在于把一大堆具体的细节按空间顺序组成一个整体（关于空间顺序法见第12单元）。在示范段落10－1，作者按照从表面到海底，从远到近的顺序描绘。在示范段落10－2中，作者按照从左到右，从近到远的顺序描绘。
4）使用有新意的明喻和暗喻
明喻（Similes）和暗喻（metaphors）可使描述更加生动。但要尽量避免使用已经用得太滥的比喻。
Exercise 10-1
Directions：Write a paragraph of description，describing a student dormitory．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Exercise 10－2
Directions：Write a paragraph of desccription，describing a natural phenomenon that you are familiar with．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
第十一单元 推展段落方法之四
第十一单元 推展段落方法之四——过程分析法
11．1过程分析法
过程分析法（process analysis）用作支配方法时，其目的是告诉读者怎样做某事，说明某事物的工作原理或某事物的制造方法。
示范段落11－1
Even if you don't know how to cook，you'll never starve to death if you know how to prepare scrambled eggs．You begin by melting one tablespoon of butter in a frying pan over low heat．While the butter is melting，break three eggs into a bowl．Add 1／4teaspoon of salt，1／4 teaspoon of paprika，and three tablespoons of milk to the eggs in the bowl and mix them for about a minute．Pour the mixture into the frying pan，break them into shreds with a fork，or stir them with a spoon until they become solid．When they are cooked，serve them with lightly buttered toast．
11．2示范段落分析
主题句：Even if you don't know how to cook，you'll never starve to death if you know how to prepare scrambled eggs．
步骤1：melt butter
步骤2：break eggs
步骤3：add salt，paprika and milk to the eggs
步骤4：mix them
步骤5：pour into the frying pan and stir them
步骤6：serve with buttered toast
11．3关于如何写过程分析段落的建议
1）按照事物发展过程的顺序解释过程
过程分析通常使用时间顺序法组织段落，因为告诉别人怎样做某件事的最容易的方法是一步一步地分析。
2）提及必要的用具、成分的分量和时机，在适当的地方提醒读者注意容易做错的地方。
3）使用列举符号表示步骤。
下面的列举符号（listing signals）常用于过程描述：
first，second，third，etc．
to begin with，then，finally，etc．
Exercise 11-1
Directions：Read the following paragraph，then find out the topic sentence，the listing signals and analyze the steps of the process．
In his will，Alfred Nobel left specific instructions as to how the winners of the science awards he endowed are to be selected．First，each year the Swedish Academy of Sciences（physics and chemistry）and the Caroline Medical Institute（physiology and medicine）solicit nearly two thousand recommendations from past laureates，university professors and other experts from all over the world．The second step is the review of recommendations received and the selections of preliminary candidates by special committees within the two Swedish institutions．The committee members are specifically instructed that those chosen “shall have conferred the greatest benefit on mankind，”and that no considerations be given to the candidates' nationalities．Next，after lengthy investigation and discussion，the final choices are made for each discipline．Finally，telegrams informing them of their awards are sent to the new Nobel laureates about one month prior to the award ceremony．
Topic Sentence：____________________________________________
______________________________________________________________
Listing Signals：_____________________________________________
Steps： 1．______________________________________________
2．______________________________________________
3．______________________________________________
4．______________________________________________
Exercise 11-2
Directions：The sentences below constitute a paragraph on the scientific methods．However，the sentences have been given in a disordered sequence．You should place them in their correct order．
a．Following this method，the reseacher first observe some aspects of nature and then poses a specific question about what he has observed．
b．Experiments based on this hypothesis are designed and conductedto test each contingency．
c．In order to answer this question，potent data are collected．
d．After thorough experimentation，the researcher validates，modifies，or rejects his original hypothesis．
e．Originating from the branch of philosophy called epistemology，what we now know as the scientific method provides guidelinesf of the systematic acquisition of knowledge．
f．On the basis of these data，a hypothesis is proposed to explain them．
The right order：______________________________
Exercise 11-3
Directions：Write a paragraph about how to prepare a barbecue picnic in the park．
______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
第十二单元 组织段落方法——时间顺序法和空间顺序法
第十二单元 组织段落方法——时间顺序法和空间顺序法组织段落的常见方法有：1）时间顺序；2）空间顺序；3）重要性顺序和；4）熟悉度顺序。在前几单元，我们曾提到写叙述段落和过程分析时用时间顺序，写描述段落时用空间顺序。在这一单元里，我们将着重讨论这两种组织方法。另两种方法——重要性和熟悉度顺序——将在第19单元讨论。
12．1时间顺序法
段落内组织细节的最简单最常见的方法是时间顺序法（time order organization）。时间顺序通常用于叙述和过程分析——先发生什么，然后怎样，再然后怎样，等等。正如我们在示范段落9－1和示范段落11－1所看到的一样。其实在你的生活中你经常运用这种方法。你也许曾经告诉你父母在学校里发生的事情。你也许向老师或同学叙述过你是怎样做一个实验的。这些用的都是时间顺序。
12．2关于如何写时间顺序段落的建议
1）写下你要记录的事件或步骤，然后按照时间顺序排列
2）确定你的写作目的，然后写出带有中心思想的主题句
3）从你列举的事件或步骤中删除与中心思想无关的细节
4）使用“first，then，the next step”等等列举符号把细节连接起来
12．3空间顺序法
段落组织的另一方法是空间顺序法（space order organization）。空间顺序主要用于描述，正如我们在示范段落10－1和示范段落10－2所看到的。空间顺序和时间顺序一样，是生活中经常使用的方法。你也许曾在信中向你父母描述你的学院，或向你的同学描述一个风景区。
12．4关于如何写空间顺序段落的建议
按照你想让你的读者了解你要描绘的场面的方式移动——例如，从左到右，或从背景到前景，或按顺时针方向，等等。
12．5综合运用空间顺序和时间顺序
有时候，尤其在描写参观时，有必要同时运用空间顺序和时间顺序，以增强段落的统一性。
示范段落12-1
We enjoyed our visit to Dr Hassan's house，perched high up on a hill．Walking up the long driveway，we approached the huge bronze door．A butler was standing in the open doorway，ushering guests into the house．Going in，we passed the oak－pannelled library and the formal dining room before we arrived at the ballroom，where the reception was being held．Under three sparkling chandeliers，more than a hundred people were enjoying champagne，hors d'oeuvres and good conversation．
12．6示范段落分析
主题句：We enjoyed our visit to Dr Hassan's house．
时间空间顺序：driveway→door→house→library→diningroom→ballroom
Exercise 12－1
Directions：Arrange the sentences into a paragraph，using the time order and adding the necessary listing signals．
—She never had a birthday party and she was twenty－one year sold．
—The party was really a successful one．
—We planned to serve fruit punch and coffee．
—We planned entertainment．
—We carefully made a guest list．
—We planned a surprise party for Mary recently．
—We included many of her friends from school，a few of her friends from her neighbourhood，and all of her brothers and sisters．
—A boy did mayic tricks skillfully；another boy played the guitar well．
—We also wanted chicken sandwiches，a birthday cake with twenty－one candles，and ice cream．
—We especially enjoyed the group singing．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Exercise 12-2
Directions：Narrate an incident from your own childhood in which you behave in a way you later regretted，using time order．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Exercise 12－3
Directions：Narrate one of your trip，either by bike，by bus or bytrain，combining time order and space order．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
第十三单元 推展段落方法之五——举例法
第十三单元 推展段落方法之五——举例法13．1举例法
举例法（examples）也是推展主题的主要方法。举例法有两种形式，一种是首先陈述自己的观点，然后举出一个或多个例子阐明观点；另一种是先举一个很长的例子，然后转入例子所要阐明的观点。
读下面段落：
Courage is the willingness to take a risk when the outcome is uncertain，and when the risk taken may involve harm，loss，or danger to the one taking it．The courageous person fears no one and nothing．He or she is undaunted by danger or peril．He or she will venture boldly into an uncertain situation，hardly giving a thought to the harm or consequences which may result to his or her person．
以上段落的缺点是乏味、含糊，不能向读者表达作者关于“courage”的看法。请看下面重写后的段落。
示范段落13-1
Courage is the willingness to take a risk when the outcome is uncertain，and when the risk taken may involve harm，loss，or danger to the one taking it．For example，in a Los Angeles suburb，a twelve－year－old girl ran into a burning house to rescue her baby brother，pulled him unconscious out of the burning bedroom，and dragged him down the stairs and outside to safety．This was arousing display of courage．The girl had been safe outside the flaming house when she remembered her sleeping brother．Disregarding her personal safety，she plunged into the flaming house to save him．
13．2示范段落分析
较之上一段落，这个段落更能清晰地传达作者关于“courage”的观点。首先，作者概述什么是“courage”，然后举出一个女孩子从燃烧着的房子中把弟弟救出来的例子阐明这一观点。
13．2关于写举例法段落的建议
1）选择恰当的例子
所选的例子应该能够恰当地支持自己的观点。
2）要表明你的例子所要阐明的观点
大多数作者使用“for example”等短语引出例子。其它常用的短语有：“as an example”，“to illustrate”，“for instance”，“an illustration of it”，“a case in point”（见第34单元）。
3）不要滥用例子
Exercise 13-1
Directions：Read the following paragraph，point out the topic sentence，and find out what example the writer uses to illustrate his point．
Despite her wealth，Madame Rubinstein had a mania for saving money．French President Georges Pompidou once rented a Paris apartment from her．She noticed that he left the building at exactlly8：50 every morning．Madame began ordering her daily taxi for 8：45 so that she could save on cab fare by following Pompidou's motorcycle escort through the heavy Paris traffic．
Topic Sentence：____________________________________________
Example：__________________________________________________
Exercise 13-2
Directions：Choose one of the given topic sentences and use an example to develop the point．
（1）
Doing part－time jobs helps increase our experience．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
（2）
You may have heard the old saying，“Self-help is the best help．”The truth of it has been proved by the successful lives of many great men and women．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
第十四单元 推展段落方法之六
第十四单元 推展段落方法之六——比较与对比法
14．1比较与对比法
有时为了说明某一事物，需要与其他事物联系起来才能阐述清楚，这就是对比或比较（comparison or contrast）。比较方法和对比方法基本一致，不同的是比较强调两事物如何相同，对比强调两事物如何不同。
示范段落14－1
Life in the city is quite different from life in the suburbs．People living in the city are constantly exposed to the hustle and bustle of urban life．But life in the suburbs is generally quiet and casual and generally more low－key than in the city．If city dwellers want to see trees and grass，they must go to one of the public parks．On the other hand，the streets of many suburban communities are lined with trees and shrubs，and each house has its own grassy yard．A person living in the city is close to many sources of entertainment，but people living in suburan areas must go into the city for entertainment．
示范段落14－2
The llama is a member of the camel family．Like the camel，the llama can live for weeks without a drink of water．Both get enough moisture from the grass，shrubs，and other plants they eat．But unlike the camel，the llama has no hump on its back．
14．2示范段落分析
示范段落14－1所用的支配方法是对比。作者对比城市生活与城郊生活。而示范段落14－2同时运用了比较和对比方法，既描绘了无峰驼和骆驼的共同点，也描绘了不同点。
14．3关于如何写比较或对比段落的建议
1）弄清比较或对比的基点
在写比较或对比时，第一步是确定比较／对比的基点。在示范段落14－1中，作者把对比基于生活步调、视野和娱乐上。在示范段落14－2中，作者把比较和对比基于无峰驼和骆驼的特性和外表上。
2）用逐事比较或逐点比较的方法组织比较或对比段落一旦确定了比较／对比基点，作者就可以用以下两种方式之一推展段落：逐事比较（item－by－item）或逐点比较（point－by－point）。
逐事比较重点放在被比较和对比的特定事物上，先叙述A事物，再叙述B事物。逐点比较重点放在两事物中每个事物的各个特征上，先叙述每个事物某一特征，再叙述每个事物的另一特征。如下面比较“a motor－cycle”和“a car”的异同的大纲所示：
Item－by－Item
Ⅰ．Motorcycle A．Expense B．Upkeep C．Safety
Ⅱ．Automobile A．Expense B．Upkeep C．Safety
Point－by－Point
Ⅰ．Expense A．Motorcycle B．Autormobile
Ⅱ．Upkeep A．Motorcycle B．Autormobile
Ⅲ．Safety A．Motorcycle B．Autormobile
3）运用连接词语保持连贯（连接词语见第34单元）
Exercise 14-1
Directions：Write a paragraph using a point－by－point comparison/contrast about the advantages of bikes over cars or
buses．The outline and the topic sentence are given．
Outline：Ⅰ．Expense A．Cars or buses B．Bikes
Ⅱ．Convenience A．Cars or buses B．Bikes
Ⅲ．Pollution A．Cars or buses B．Bikes
As compared with cars or buses，bicycles have unique advantages for Chinese people．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Exercise 14-2
Directions：Write a paragraph of contrast，contrasting women today with women in the past（hints：social status，family status，etc．）．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
第十五单元 推展段落方法之七——下定义法
第十五单元 推展段落方法之七——下定义法15．1下定义法
下定义（definition）就是解释某事物是什么，不是什么。写下定义段落时，通常把概念或要下定义的事物置于一个大的类别中，然后解释该事物与同一类别的其它事物有何不同。下定义法多用作推展段落的辅助方法。
示范段落15－1
A pencil is an instrument for writing on paper．It is of cylindrical shape and can be held between the first two fingers of the hand．It is about 6 inches long and 1／4 inch wide．At the end there is usually an eraser attached to the pencil by a surrounding metal band．Lead is the material which is used in making the marks on the paper，and a sharpener is needed to keep the pencil in good working order．Pencils are made of various kinds of wood．
15．2示范段落分析
主题句：A pencil is an instrument for writing on paper．细节：shape，material
15．3关于如何写下定义段落
1）以正式的定义开始
一个正式的定义段落通常把要定义的术语置于一个概类中，然后指出该术语与其它同类别事物有什么不同。在示范段落15－1中，要定义的术语是“pencil”，属于概类“instrument”。
2）用描述、举例或比较对比方法扩充定义
在正式的定义之后，必须更详细地解释该术语的意思，在示范段落15－1中用的是描述法，在示范段落13－1中，扩充“courage”概念用的是举例法。比较对比法也可以用于扩充定义，对比法陈述该事物不是什么，比较法陈述该事物象什么。
Exercise 15-1
Directions：Read the following paragraph，point out the topic sentence and find out what method（s）are used to expand the defintion．
Chemistry is that branch of science which has the task of investigating the materials out of which the universe is made．It is not concerned with the forms into which they may be fashioned．Such objects as chairs，tables，vases，bottles，or wires are of no significance in chemistry；but such substances as glass，wool，iron，sulfur，and clay，as the materials out of which they are made，are what it studies．Chemistry is concerned not only with the composition of such substances，but also with their inner structure．
Topic Sentence：____________________________________________
Method（s） used：_______________________________________
Exercise 15－2
Directions：The definition of“an ice－box”can be，“An ice－box is an appliance for storing food at low temperature．”Now use the method of description to expand the definition．
An ice－box is an appliance for storing food at low temperature．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
Exercise 15-3
Directions：Give the defintion of friendship and then use an example to expand your definition．
________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________