一篇议论文能否获得高分与其中心段落主题句的质量不无关联，而主题句质量的高低则又取决于审题的好坏和论据的选择(即所选的论据在逻辑性、说理性、准确性及与主题内容的关联性等方面是否都经得起推敲)。需要明确的是，中心段落只应有两个组成部分：段落的主题句和支持主题句的论据。
段落的'主题句也应有两个部分组成，即：主题句=主题+作者对主题的看法或态度，两者缺一不可。假设应试者被要求写一篇有关吸烟的议论文，那么 SMOKING 就是中心段落的主题。请看下面这个主题句：
Smoking is a habit of many men.
该主题句暴露出两个问题：(1)作者审题不清;(2)作者没有表明对主题的看法或态度。
一般说来，议论文要求应试者阐明自己对某问题的看法或态度。因此当我们拿到议论文的题目以后，要认真审题，权衡某事的利与弊，然后确定我们的立场。
如何构建段落的主题句呢?
拿到议论文的题目以后，经认真审题后，用英文列出你所能想起的与主题有关的例证。我们还用吸烟这个话题为例：
SMOKING
1. Smoking can cause such a disease as lung cancer.
2. Reports say that merely 3 grams of nicotine can kill a large animal.
3. Experts say that smoking one cigarette can reduce one’s life by about 15 minutes and that chain smoking is even more hazardous.
4. Smoking after a meal can also disturb one’s digestive system.
5. Heavy smoking can seriously affect an adult’s sexuality.
6. Smoking does harm to second-hand smokers as well.
7. Smoking makes one’s mouth smell.
8. The life expectancy of smokers is shorter than that of nonsmokers.
9. Smoking in bed may cause fire..
