句子的完整性包括两个方面，即意思的完整性和结构的完整性。

意思的完整性是指一个句子应该表达一个相对完整的思想。

结构的完整性指的是句子在语法结构方面没有缺损。如：

It is incredible to many people. Cigarette smokers spend money for illness.

原句中it的意思不明确。可用it作形式主语，使句子结构完整。即：It is incredible to many people that cigarette smokers spend money for illness.

为了使句子保持结构完整，还要注意避免融合句(Run together Sentence)，所谓融合句，就是两个或两个以上的句子之间没有适当的标点符号或连词而融合在一起。如：

I do not care for any more fruit, I have had enough.

可改成：I do not care for any more fruit, for I have had enough.

(2)连贯(Coherence)

句子的连贯性包括两点，即句子各部分之间意义上的连贯和结构上的连贯。如：

1)She told my sister that she was wrong.

句中代词she所指意思模棱两可，可用：“You are wrong,”she said to my sister.

2)On squeezing on to the bus, my wallet was lost.

动名词的逻辑主语与句子主语不一致，可改成：

On squeezing on to the bus, I lost my wallet.

(3)清晰(Clarity)

句子的清晰度包含以下四点：句子的主要意思突出；修饰语运用正确；修饰语位置适当；标点符号正确。如：

1)They were just turning the corner, when they heard the noise of a shot.

该句主要意思不突出，句子要表达的主要信息应放在复合句的主句中，所以这一句可改成：

They heard the noise of a shot, just as they were turning the corner.

2)I have interesting something to tell you.

(1)段落和段落的组成

段落(Paragraph)是扩展中心思想的一组意义密切相关的句子。它本身是一个单元(Unit)，同时又是文章的基本部分。

段落一般由三部分组成：主题句(Topic Sentence),扩展句(Development Sentence)和结论句(Concluding Sentence)。

主题句点出段落主旨，各段落的主题句构成一篇文章的骨架，阐述全文的中心思想(Central Idea)，扩展句说明主题句或为主题句提供论证，结论句总结、归纳或概括主题句所点出的主旨。

(2)过渡词

过渡词(Transitional Words)是一种关系指引词，是连接句子与句子、段落与段落的纽带。过渡词一般由副词或起副词作用的短语承担。此外，代词、连词、上下文的近义词等也可作过渡词。过渡词能使文章启、承、转、合，融会贯通，连成一体。

过渡词的分类根据过渡词在文章中的作用，大致可分四类：

1)用于“启”的过渡词语

first, first of all, at first, in the first place, firstly, to being with, to start with, recently, now, at present, in recent years, and so on.

2)用于“承”的过渡词语

second, similarly, in addition, besides, then, furthermore, moreover, what is more, what is worse, for example, for instance, certainly, surely, obviously, in other words, especially, particularly, in particular, indeed, still, third, truly, in fact, in plain terms, for the most part(基本上)，at the same time, no doubt，and so on.

3)用于“转”的过渡词语

however, on the other hand, on the contrary, in contrast, in any case, at any rate(无论如何)，conversely(相反地)，nevertheless(虽然如此)，otherwise, or, or else, while...,whereas..., but, despite..., in spite of ..., yet, instead，and so on.

4)用于“合”的过渡词语：

consequently, as a consequence, therefore, as a result, above all, thus，after all(毕竟)，generally speaking, in general, finally, at last, eventually, hence, inshort(总之)，in conclusion, in a word(总之，简言之)，in sum(总之)，on the whole(就整体而言)，to sum up，and so on.

(3)段落扩展

段落扩展(Paragraph Development)是根据主题句的思想来阐明问题的某一方面。好的段落应该是主题单一、内容完整、连贯，长度适中。这里介绍几种最常用的扩展方法，以供参考。

1)描述法(Description):描述法是段落扩展中最常用的一种方法。描述一个过程或程序时，常用一般现在时的被动语态，这是“一般描述”；报导某一特定的程度或过程时，其涉及到的只是过去某一特定的情况，所以经常使用一般过去时的被动语态。如果描述不涉及到某特定的过程或程序，则经常用一般现在时的主动语态。此外，在描述过程或报导事件时，顺序很重要。

2)举例法(Exemplification):用具体事例来阐述主题句的中心思想。

3)比较与对比法(Comparison and Contrast):比较与对比是阐述段落主旨的常用方法；通过比较指出事物的异同，通过对比找出事物的差异。

下面列出须熟记的10个表示比较的常用句型：

句型a.A is different form B in that…

句型b.With regard to…, A is bigger than B

句型c.A and B are different in every way(respect)

句型d.One of the differences between A and B is that :

句型e.A and B have a little(something, much etc.) in common

句型f.A is quite (completely, entirely, totally) different from B

句型g.A is not quite as/so big (expensive, interesting etc.) as B

句型h.On (the) one hand, A is (has, does) :;on the other (hand), A is (has, does):

句型i.A is exactly(precisely, just, practically, more or less, almost, nearly, approximately, about) the same as B

句型j.A is much(a great deal, a lot, considerably, somewhat, a bit,

alittle, slightly, hardly, scarcely, only just) smaller (bigger, cheaper) than B[ZK)]

4)因果法(Cause and effect):通过分析事物发生的起因，来说明由此而产生的种种结果。

下面列出须牢记的8个表示因果的句型例句：

句型a.Bad weather is due to caused by an increase in air pollution.

句型b.If /When there is an increase in air pollution, (then) the weather gets bad.

句型c.An increase in air pollution often causes/leads to/results in/

produces worse weather.

句型d.As/Since/Because/Now that the air pollution has increased, the weather gets worse.

句型e.The cause ofreason for worse weather was an increase in air pollution.

句型f.The/One resulteffectconsequenceof an increase in air pollution is worse weather.

句型g.The air pollution has increased.

So/Now/Thus/Hence/Therefore/As a
result/Accordingly/Consequently/Because of this/For this reason, the weather is worse.

句型h.The weather gets worse, as/since/owing to/there is/because of/as a result of/on account of an increase in air pollution.

除上述四种扩展段落的方法外，还有许多其他的方法，如综合法、归纳法、分析法和演绎法等。