NO.1 定义

句型转换是句子类别的转换，其目的在于检测学生运用各种句型的表达能力，才能在考试的评分中得到较高档次的分数。这就要求学生对所学的句子结构和词形的变化做到概念清楚，懂得各种句型如何转换，运用准确，这有利于提高英语口语和书面表达能力。

NO.2 简单句与复合句之间的互变

很多复合句和简单句可以互变，意思上不发生太大的变化。在很多情况下，是将复合句里的从句变为一个短语。

不论是主语从句、表语从句、宾语从句、定语从句还是状语从句，在一定的情况下都可以这样转换。

主语从句有时可以和短语互换，它既可以是不定式短语也可以是动名词短语。

(1) When and where we should hold the meeting is still to be discussed．

→When and where to hold the meeting is still to be discussed．

(2) It worried her a great deal that her son would stay up so late．

→Her son’s staying up so late worried her a great deal．

(3) What we had to do was to stand there，trying to catch the offender．

→We had to stand there to catch the offender．

表语从句有时可以和短语互换，与它互换的可以是不定式短语和动名词短语。

My idea is that we should do it right now．

→My idea is to do it fight now．

在某些动词的后面宾语从句可以和一个动名词短语或不定式短语互换．

(1) I regret that I had told you the secret．

→I regret telling you the secret．

(2) They don’t know whether they shall carry out the old plan or not．

→They don’t know whether to carry out the old plan or not．

有些定语从句可以和一个不定式短语，分词短语或介词短语互换。

(1) Can those who are seated at the back of the classroom hear me?

→Can those seated at the back of the classroom hear me?

(2) What are the most important measures we should take?

→What are the important measures to be taken?

(3) The young man who was in the possession of the firm was at a desk．

→The young man in the possession of the firm was at a desk．

状语从句和短语互换的情形很多，常用分词短语来替代状语从句，表示时间、原因、条件。用不定式短语来替代状语从句，表示目的、结果、原因；另外介词短语可以表示时间、原因、条件、让步等状语

(1) Given more time，we could do the job much better．

(2) They started off early so that they could catch the first bus

→They started off early so as to catch the first bus．

(3) I could swim when I was eight years old．

→I could swim at the age of eight．

NO.3 复合句与并列句之间的转换

英语中的并列句在一定的条件下可转换为含有条件、时间、结果、让步、原因等的复合句；而反过来复合句也可以转换为并列句。

如：

并列句转换为复合句，常把其中的一个分句转化为从句，再根据句意加上相应的从属连词。

(1) It’s foggy today，so we can’t see the distant hills．

→Because it’s foggy today，we can’t see the distant hills．

(2) Study hard，and you will get good marks．

→If you study hard，you will get good marks．

复合句转换为并列句，需把一个从句转换为一个分句，再加上一个合适的并列连词或者分号。

(1) Though he has been told several times，he still can’t understand it．

→He has been told several times，but he still can’t understand it．

(2) If you study hard，you will make great progress in your English studies．

→Study hard and you will make great progress in your English studies．

NO.4 简单句与并列句之间的相互转换

简单句转换为并列句，常把简单句中的某一短语转变为并列句中的一个分句。

(1) Tom is too young to go to school．

→Tom is very young and he can’t go to school．

(2) She got up very early to meet her parents at the station．

→She wanted to meet her parents at the station，so she got up early．

并列句转换为简单句，常把其中的一个分句变为短语，这一短语通常是介词短语、不定式短语、分词短语、with的复合结构或独立主格结构。

(1) They cancelled their trip to Yellow Mountain for it rained heavily．

→They cancelled their trip to Yellow Mountain because of the heavy rain．

(2) His mother was ill，so he had to stay at home to look after her．

→His mother being ill，he had to stay at home to look after her．

综上所述，简单句与复合句之间互换：介词短语、不定式短语、动名词短语、分词短语；复合句和并列句之间的互换：分句换从句，从句换分句，加连接词辅助；简单句与并列句之间的互换：短语变分句，分句变短语。

本章节是语法知识点最后一章，要再次学习请看之前发布的文章，之后会总结阅读技巧以及方法。