_________________
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
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：________________________________________