主题句作文也叫做段首句作文，就是给出每一段的第一句话——往往是表达该段中心思想的主题句，然后考生加以扩展发展成段，最后成篇。这种属于控制性或指导性的作文，考生应严格遵循题目及各段首句展开思路，完成文章。

　　主题句作文的写作可依照以下步骤进行：

　　1.准确理解文章标题

　　标题是文章主题的高度概括，限定了写作范围，考生的写作应以此展开。只有准确理解文章标题，写作时才不会跑题，并把握文章的体裁。

　　2.找准关键词，确定段落内容

　　段首句提供了该段的中心思想，但是为了把握段落扩展的范围和方向，为了保持和主题的一致性，考生一定要找出关键词(key words)——关键词是段落和文章的核心，文章是否切题，段落是否环环相扣，都与确定关键词有关。

　　3.确定段落的发展方向

　　这一步就是要考虑文章的写作方法，突出主题。要根据不同的段首句选择不同的段落发展方法。主要方法有例证法、因果法、列举法、比较法和对照法。这些方法的灵活运用可以使文章脉络清晰，逻辑性强。

　　4.搞清段落与文章之间的关系

　　给出的段首句实际上是文章的大体结构和内容。因此，应通过对标题和关键词的分析来统筹各段的写作内容，避免内容的重复。各段所选择的扩充材料也应具有代表性，能够充分证明、解释主题句的内涵。

　　【经典范文】

　　Directions:

　　Title: Help Children to Be Independent

　　The topic sentence is provided as follows:

　　1) Today in China, many families have only one child.

　　2) There are some ways to help children to be independent.

　　3) To be independent is good for the children.

　　You should write 160~200 words.

　　Help Children to Be Independent

　　Today in China, many families have only one child. So the children usually doted upon by all family members. Gradually some of them get used to depending on their parents and lack the ability to solve problems independently.

　　There are some ways to help children to be independent. Firstly, the child should have a chance to see the world around him. He must understand that there’re various competitions in this world, and everyone can find his right position in the society only by individual efforts. Secondly, the parents should give the child enough help to make him feel comfortable. It’s impossible to ask a child not to depend on parents at once. A child needs help from the beginning. Without any help, the child may lose his faith. Thirdly, parents should let his child make decisions, which can temper his ability to deal with problems. A child should be praised when he is successful or when he fails.

　　To be independent is good for the children, because no parents can accompany the children for the whole life. It is the child himself who is responsible for her own fate. Only an independent person can live and succeed in this world.

　　【练习】

　　Directions:

　　Title:Problem of Piracy

　　The topic sentence is provided as follows:

　　1) Nowadays, the problem of piracy has become more and more prominent.

　　2) Piracy has caused great loss to the writers, inventors and legitimate producers.

　　3) Even so, this problem has not received due attention yet.

　　You should write 160~200 words.

　　【答案】

　　Problem of Piracy

　　Nowadays, the problem of piracy has become more and more prominent. Books, tapes, videos and other high-tech products almost all have been pirated. When a new product comes into market, very probably, its pirated counterpart will soon make its appearance in the market too.

　　Piracy has caused great loss to the writers, inventors and legitimate producers. Because the pirated products often cost much less than the genuine ones, they enjoy a pretty good selling in spite of their relatively poor quality. The genuine products, on the contrary, sell poorly. This happens especially to some high-tech products, whose prices are often exorbitant. Then, in the case of the pirated editions of books, they are so misprinted. Sometimes they may even bring the names of their authors under dishonor.

　　Even so, this problem of piracy has not received due attention yet. Consumers have not developed the consciousness to resist the pirated products. Rather, they tend to be tempted by the great gap between the prices. Furthermore, the governments have not taken enough measures to stop piracy effectively. Really, we have a long way to go to fight against piracy.

    来源：《2011考研英语写作秘笈》