作文是衡量学生英语综合水平和应用能力的一个重要指标，也是大学英语四级考试的一个重要内容。因此写好作文对于参加英语四级考试的同学来说很重要，今天小编为大家准备了以下内容，希望对大家有帮助。　

　　议论文中心段落的主题句及其论据、议论文中常用的词句与短语

　　(1) 议论文中心段落的主题句及其论据

　　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..

　　Smoking is a bad habit that does a lot of harm to human health. Cigarette smoking does great harm to human health. In many cases, cigarette has proved to be the direct cause of such a fatal disease as cancer-hence its nickname, "Cancer Stick". Experts say that smoking one cigarette can reduce one’s life by about 15 minutes and that chain smoking is far more hazardous. Recent findings of medical research show that even a tiny drop of nicotine (about 3 grams in weight) can kill a large animal like a horse. Some medical reports have also proved that heavy smoking would seriously affect an adult’s sexuality, and smoking after a meal also disturbs one’s digestive system. Cigarette smoking not only jeopardizes the physical health of a smoker, it also affects the health of a nonsmoker who passively inhales the polluted air into his or her lungs when he or she is exposed to a winding shroud of cigarette smoke. The impact on such passive smokers (also called second-hand smokers), according to the experts in the medical field, can be even more damaging, and that is why smoking is usually prohibited in most public places. (196 words)

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