（2） 语篇的连贯性
        英语议论文的段落多采取直线展开式，即段落开始直接切入主题，并给出事实、例证、推理等。英语议论文段落这种展开方式是形成其语篇连贯的基础。语篇的连贯是指段落中各句的意义通过某种有序的排列（如时间顺序、因果顺序、逻辑顺序等）而相互关联。在论述该段落主题的时候，每后一个句子都是建立在前面一个句子的基础之上的。如果去掉段落中的一个句子，这种连贯便会受到影响，就会造成读者在理解上的困难。
        
        3． 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..

       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：
        (1)
        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 (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. (211 words)