主题句作文是CET-4写作中常见的一种作文形式。这是一种控制性作文，旨在控制考生的写作范围，要求考生按所给每个段落的第一句续写，完成各段落，但同时它也为考生提供了段落扩展的有利条件，有利于考生在文章的结构和内容安排上不出偏差。因此，主题句作文审题的主要任务之一是审段首句。审题时抓住各段首句的关键词语，仔细斟酌每个段首句的内涵和外延，并把段首句同文章的标题联系起来分析，找出标题与各段首句之间的关系，以确定段落的扩展方式和材料的筛选。在具体写作时要以段首句为线索，合理安排有关材料或细节，将段落充分展开，并保证各段落在意义上连成一体，形式上互为统一，语气上一气呵成，否则就会偏离主题。下面以1989年6月的作文“What Would Happen If There Were No Power?”为例：
What Would Happen If There Were No Power
1. Ever since early this century, electricity has become an essential part of our modern life.
2. If there were no electric power,
第一个段首句所包含的信息是：电在现代生活中的作用。句中的关键词是an essential part of our modern life， 即该段的中心思想。因此，可通过举例、说明、分析等手法扩展完成该段落，阐明电在现代生活中的作用。
Ever since early this century, electricity has become an essential part of our modern life. It is much used in both our life and production. We use electricity to light our houses, carry our messages through space, work computers, show us the inside of our bodies, and drive all kinds of machines, such as washing machines, air conditioners, pumping stations and various machines on the production line.
第二段“If there were no electric power”这是一个主从复合句，虽然只给出了从句部分，但它表明该段与第一段是转折关系。因此，第二段应写成与第一段意思相反，形成对照的一个段落，说明“如果没有电”，现代生活将会是什么样。
If there were no electric power, the modern world would be in great trouble. Many of our industries would stop production because the motors that power the machines would fail. The transportation systems would fall apart without a supply of electricity. Electric trains would all stop, and motor vehicles could not be operated. For the same reason, aeroplanes could not fly. Probably the worst effect would be felt on the communications systems. The telephone, radio, television and radar would be put out of action.
Therefore there are two points we must pay attention to. First, we should save electricity and energy resources such as coal and oil with all our efforts because most of the electricity we use is produced by machine with coal or oil as fuel. On the other hand, people should also explore other sources of power, for instance, water, sea tide, wind power, and harness solar energy and energy from within the earth, and so on. Scientists have to discover a substance that will replace electricity.
如：1998年6月的作文“Numbers and Luck”
Directions: For this part, you are allowed thirty minutes to write a composition on the topic
Numbers and Luck. You should write at least 100 words and you should base your composition on the outline (given in Chinese) below.
写作标题及汉语提纲将短文定位为论说文。前两段要求考生说明目前社会上对 “数字是否可以带来好运” 这一问题所持的截然相反的两种观点。最后一段要求考生说明自己对这一问题的看法。当然，考生还必须申明自己持这种观点的理由。
Some people say that some numbers will bring them good luck. Take “8” for example. The Chinese pronunciation of the number “8” has almost the same sound as that of the Chinese character “发”, which means making a fortune. Therefore, many Chinese people spend a lot of money to get their telephone number or car number to include this number “8”. They believe without any doubt that the number will bring them money.
However, others don’t believe that numbers have any connection with good luck. They think such an idea is only an ignorant and superstitious belief. A number is one thing, and good luck is another. They will say: How can you ever have any good luck simply because of some lucky numbers, even if you don’t work hard, don’t have good opportunities and don’t get along well with the people around you.
So far as I am concerned, I agree with the latter. Obviously, such belief is only a kind of superstition. Perhaps it holds true for some cases, but often it does not. Numbers can never bring good luck to a person at all and our fortune is in our own hands. Therefore, everyone can have good fortune only if he tries his best. Let’s always remember “Opportunities are only for the prepared mind” and “No pains, no gains.”
图表作文只出现过两次，即1991年6月的Changes in People’s Diet (人们饮食状况的变化)和2002年6月的Student Use of Computers（学生使用计算机）。图表作文要求用恰当、准确的文字来解释说明图表。其目的是通过对所给数据进行比较分析，从中找出某种规律或得出一个结论。故图表作文实质上是说明文和议论文甚至描述文（需要对图表描述）等体裁的结合体。根据所给提纲条目，第一段需先用描述文的写作方式将图表内的重要数据用语言表达清楚，然后在第二段内分析图表所表现出的观点，即论证该观点。第三段为结尾段，即重申图表所揭示的问题，做出合理可信的预言。
以1991年6月Changes in People＇s Diet 为例：
1．State the changes in people’s diet in the past five years.
2．Give possible reasons for the changes.
3．Draw your own conclusions.
Year Food 1986 1987 1988 1989 1990
Grain 49% 47% 46.5% 45% 45%
Milk 10% 11% 11% 12% 13%
FruitVegetable 24% 22% 20% 20% 21%
Meat 17% 20% 22.5% 23% 21%
Total 100% 100% 100% 100% 100%
这是一篇图表附提纲作文。图表作文的写作过程通常是读图 — 整理素材 — 拟订提纲。本试题既给了标题和统计表，又给出了提纲。因此，写作过程就可缩减为紧扣主题读图 — 按所给提纲的要求分析、整理和归纳图表的数据。
As we can see from the table, great changes have taken place in people’s diet over the period from 1986 to 1990. While more and more high-nutrition foods such as milk and meat are consumed by people, the amount of grain consumption, once the main or even the only food for Chinese people, is continuously decreased.
There are several reasons for such changes. Firstly, with the development of our country’s economy, people become more and more wealthy, so they can afford to buy expensive high-energy food. Secondly, nowadays, people believe that certain amount of high-nutrition food is quite necessary to their health. In order to keep their body healthy, they should add nutritious food to their traditional diet.
So, from the above table, we can see that people’s living conditions have greatly improved, and we can hope for a more scientific and reasonable diet for Chinese people in the future.
For this part you are allowed 30 minutes to write a letter. Suppose you are Zhang Ying. Write a letter to Xiao Wang, a schoolmate of yours who is going to visit you during the week-long holiday. You should write at least 100 words according to the suggestions given below in Chinese:
I am delighted to learn that you are going to visit me during the week-long holiday. My parents will also be happy to see you again. I am sure you will enjoy every minute of your stay here.
I have made a rough plan so that we can enjoy the seven-day holiday in a leisurely way. I know you are fond of swimming. Therefore, we can go swimming in the river that lies not far away from my home. I think it would be very pleasant and refreshing to swim in such hot summer days. Besides swimming, we can go climbing a mountain. A mountain about two miles away from here is beautiful and it is worth climbing. We can go there on foot. When we climb to the top of the mountain, we can have a wonderful bird’s-eye view of the whole village. If it is so hot that you don’t want to stay in the open air, we can stay at home. As in every big room of my home there is an air-conditioner, we can watch TV, play VCDs or read books very comfortably.
But remember to phone me before you set off. There is no need for you to take anything along, since I’ll have prepared everything for you by your arrival.
I am looking forward to seeing you soon.
How I Finance my College Education
1．上大学的费用（tuition and fees）可以通过各种途径解决。
While the cost of college education has risen sharply in the past few years, students have several ways to pay for their college tuition and fees. First, they may depend on their parents. Many students do not like this way because they think, as college students, they are now responsible for themselves. They generally turn to part-time jobs for their economic independence, and this is the second way for them to pay for tuition and fees. Third, some excellent students can win a yearly scholarship which will solve this problem well. I believe this is the best way since they will become successful in both their study and their life. Lastly, banks will offer poor students low-interest loans so that students can put their hearts into the study and repay the banks in the future.
As for me, I choose to take a part-time job. Then I can finance my college education by myself.
此篇文章忽视了题目是“How I Finance my College Education”，中心是“我”的计划，应该围绕“我”如何筹措上大学的费用，把重点放在第二段而不是第一段。改后的文章为：
While the cost of college education has risen sharply in the past few years, students have several ways to pay for their college tuition and fees. Mostly their parents will pay. Many students may find a part-time job. Excellent students can win a yearly scholarship and poor students will easily get low-interest loans from banks.
As for me, I choose to take a part-time job. I do not want my parents to pay for my college education since I have grown up. In the future I will have to live by myself, supporting my own family and my parents. And a part-time job is the right step I should take. Besides, I may get more experiences through a part-time job. This is how I will finance my college education.
例如1996年1月的作文“The Two-day Weekend”，第一段是双休日给大学生带来的好处，有的同学这样写到：
We have been thrown into a competitive society. Everybody around us is working hard to build his happy life, and if we do not want to lag behind, we have to work even harder. College students have to face competitions in both their study and their life. Several years ago it was said that they lived comfortably in the “tower of ivory”, but now they are living like workers bees. The problem is that they do not have much free time … .
这位同学的文笔不错，也不是没有逻辑，但写了这么多，还是无法让人跟“双休日给大学生带来的好处”联系起来。如果他先把主题句“The two-day weekend has given college students much freedom.”写出来，再围绕主题句来写双休日给大学生带来的好处，效果就好了。
He was stronger than I am. He often protected me when someone wanted to strike me. I was cleverer. He often wanted me to make something like toy guns.
He was stronger than I am; therefore, when someone tried to strike me, he would protect me. But I was cleverer; (hence) he often asked me to make some toy guns for him.
例如1998年1月的作文 “Harmfulness of Fake Commodities”中的第一段“目前社会上有不少假冒伪劣商品。为什么会有这种现象？”，有的考生这样写：
Nowadays, we are very worried to find out that there are many fake commodities in the society. Why is this possible? I think there are two big reasons: first, some manufacturers are greedy. They are willing to produce fake commodities. They may give their souls to the devil for money. Second, some customers do not have the idea of protecting themselves. After they are cheated, they only cry for a while and do nothing else.
Nowadays, it is rather disconcerting to find that there are many fake commodities in the market. How has this phenomenon arisen? I think that there are two major reasons: first, some manufacturers’ greed for money has led to the production of fake commodities. As long as they can make money, they are ready to sell their own souls to the devil. To sell their fake commodities to customers is certainly even easier. Second, some customers’ awareness of self-protection is too weak. Having been deceived by the treacherous manufacturer, customers generally do nothing other than complaining for a while. They never have the thought of taking the cheat to court.
在范文中，“society” 换成了”market”，“this”换成了“this phenomenon”，使名词所指的对象更加具体。”very worried” 换成了”rather disconcerting”，更能表达出内心不安的感受。 “reasons”一般用“major”而不用 “big”表示“主要的，大的”意思。
动词“are willing to produce fake commodities”是因为他们“greedy”， 后边用了动词词组“led to”把这两个句子连接起来，更自然，更富有逻辑性。后文对前文最成功的改进是把前文的“give their souls”换成了“sell their own souls”， 一方面更贴切，另一方面和后面增添的“sell their fake commodities”相对照。此外，后文把前文的“cheated”换成“deceived”，“cry”换成“complain”，都表现了更丰富的用法和更准确的思想。