主题句的写作要求1.完整的结构Fragment: Teaching a child good manners.Complete: Teaching a child good manners is fun. / Teaching a child good manners is no easy task. (分别以这两句为主题句的段落，其发展方向肯定会不同。
) Fragment: The importance of blood.Complete: Blood serves our body in three important ways.2.明确的观点Unclear: I know Smith.Clear: Smith has a good sense of humor.Smith is the meanest man I ever know.Unclear: People care about sports. /Sports influence our life.Clear: Sports can keep people healthy and strong.Sports benefit us in many ways.Sports have their negative aspects.Sports sometimes can do some harm to people.3.具体的内容General: Electricity is important.Specific: Electricity has become an essential part of modern life. /If there were no electric power, our modern world would be in trouble.练习：I 选出与下列主题句不符的扩展句：1.. The sense of humor is mysteriously bound up with nationalcharacteristics. A Frenchman, for instance, might find it hard to laugh at a Russian joke. In the same way, a Russian might fail to see anything amusing in a joke which would make an Englishman laugh to tears.A. There are always different jokes.B. My brother often makes jokes.C. Jokes, despite their differences, have the same humor.D. Whether we find a joke funny or not depends on where we have been brought up.2.. Retirement gives one a feeling of uselessness. Such apsychological problem often brings physical problems. It is the feeling of emptiness that gradually kills the retired. With retirement there will be a decrease in income. Unless they plan carefully, the retired will get into economic problems.A. The retired are a problem of our society.B. People should not retire until unable to work.C. Retirement can bring many problems for the retired.D. We should do something for the retired.3.. They now can do most of the things people can do, thoughmost scientists agree that computers cannot take the place of humans. Who knows what the computers of tomorrow will be like? Will they make life better, or will they bring suffering to people? People today will have to decide how to use the computers of tomorrow.A. Computers are a great helper.B. Computers compete with man for jobs.C. Recently there have been great changes in computers.D. We need greater efforts to develop computers.4.. For example, there are so many idioms in English. Anotherexample is the spelling. Learners have to spend a lot of time learning them by heart. And they must put practice into the first place. The more they practice, the more they would benefit. So English learners are required to speak more and read more. English becomes easy only in practice.A. You have to make greater efforts to learn English well.B. To learn English well, you should practice more.C. English, as a language, has its difficult points to learn.D. English is a special language.5.The human brain is at least 10.000 times more complex than a computer. What’s more,computers cannot make decisions on their own. They need detailed instructions from human beings in order to operate. .A. So computers are great inventions.B. So a computer is a computer.C. So they need further development.D. So computers can never replace human brains altogether.(说明：本例中主题句在段尾，与段尾句重合。
如果将主题句至于段首，则可以写成：Despite all their advantages, computers can never replace the human brain.)II 改写下列句子，使其成为合适的主题句：1.Poor: I am going to talk about advertisements.Improved:2.Poor: We are dependent upon the sun.Improved:3.Poor: Water is necessary.Improved:4.Poor: I like sports.Improved:5.Poor: Learning a foreign language is difficult.Improved:III 给下列段落加上主题句：1.. One factor is the amount of sunlight received. Altitude,or the height above sea level, also determines climate. The oceans have an effect on the climate of adjacent land. In addition, climate is influenced by general circulation of theatmosphere.2.. You should plan your time carefully in order to haveadequate time form both work and play. When you begin to work, you should find a good place to concentrate on your study. Before you begin to read more carefully, it is better to skim first. You should take notes and go over them regularly to make reading material more meaningful. You should develop a good attitude about tests. Improving you study habits will improve your grades.3.. In towns and in villages, on farms and in factories,machines have made life easier than it used to be. The machines use energy, and energy is needed for heating, lighting, communications, carrying goods –everything. Factories and industrial plants use a great deal of energy to make the things that we use and buy and sell.4.. For one thing, the food is generally cheap. Ahamburger at McDonald’s, for example, costs about one half as much as a similar meal at a regular “sit down”restaurant. Another advantage of the chains is their convenience. For busy working couples who don’t want to spend the time or effort cooking, fast-food restaurants offer an attractive alternative. And, judging by the fact that customers return in increasing numbers, many Americans like the taste of the food.5.Albert Einstein, one of the world’s geniuses, failed his university entrance examinations onhis first attempt. William Faulkner, one of America’s noted writers, never finished college because he could not pass his English courses. Sir Winston Churchill, who is considered on of the masters of the English language, had to have special tutoring in English during elementary school. .IV 给下列段落加上主题句和结尾句：结尾句特点：1.在逻辑意义上，与主题句和争端思想内容一脉相承。