名师精讲大学英语四级议论文写作课程笔记二_大学英语写作

名师精讲大学英语四级议论文写作课程笔记二

　　根据上面所列出的七个句子，我们可以选择以下两个主题句，即：

　　1 Smoking is a bad habit.

　　2 Smoking is a bad habit that does a lot of harm to human health.

　　第一个主题句表明了作者的态度，但不如第二个具体，因此在展开中心段落时不仅要谈吸烟对人体健康的不良影响，还要涉及吸烟在其它方面造成的危害。这样的段落考生较难掌握。因此主题句越是相对地具体段落就越好展开。但这并不等于说第一个主题句不好;如果主题句太过具体，段落可展开的范围就会过窄。如果范围较窄，有些考生所能列出的例证就会相对较少，整篇文章写下来后可能达不到所要求的字数。因此选择哪一个主题句要视具体情况而定。

　　用于支持段落主题句的论据其实就是我们开始列出的那些例证，但应视主题句所涉及范围的大小而有所取舍。下面我们就上面的两个主题句分别构建两个不同的中心段落：

　　Smoking is a bad habit. For one thing, smoking in bed may cause a terrible fire. For another, regular smoking makes one s mouth smell bad. And worst of all, 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 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 , 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.