二、主题句
通过审题，我们知道了写作的思路。下边我们就谈怎么样写。第一步就是要写主题句。主题句是确保不跑题的前提，只有不跑题才有可能得及格分。写主题句最保险的方法就是把各要求句译成英语。例如上述作文的三段主题句分别为：
☆ It is very necessary to be a good university student.(议论体主题句)
☆ There are several respects of necessities to be a good university student.(说明体的主题句)
☆ What I will do in the future is the following.(描述题的主题句)
如果要求句是英语就可以把它扩充成主题句，例如这样的一篇做文：
Good Health
(1) Importance of good health
(2) Ways to keep fit
(3) My own practice
这样的作文的要求句就可以扩展成主题句。扩展后三段的主题句分别为：
☆ It is very important to have good health. (将名词importance变成形容词important)
☆ There are four ways to keep fit for me.(用there be句型)
☆ My own practices are the following.(采用原词)