英语学霸养成记之动词不定式特殊用法解析

1.不定式的进行式：to be doing

当谓语所表示的动作或状态发生时，不定式所表示的动作正在进行，这时要用不定式的进行式。

（1) They are said to be building another bridge across the Changjiang River.

（2) He pretended to be doing his homework carefully when his mother came in.

2.不定式的完成式: to have done

同其他非谓语形式一样，不定式的完成式表示不定式的动作先于谓语动作。

（1)I’m sorry to have done that, I didn’t mean to be so rude.

（2)Between 1850and 1910 the bison population is thought to have fallen from 60 million to just a few hundred.

3.不定式的被动式: to be done

当不定式的逻辑主语同不定式具有逻辑动宾关系时，不定式要用被动式。

But some people don’t want good farmland to be built on.

good farmland是句子的宾语，to be built on是宾语补足语，宾语和宾语补足语之间总是具有逻辑上的主谓或主表关系。因此，good farmland是不定式to be built on 的逻辑主语，同时它们又具有逻辑动宾关系，不定式必须同被动式。

He has asked to be introduced to the pianist.

不定式短语to be introduced to the pianist的逻辑主语是句子的主语he，同时he同introduce又有逻辑上的动宾关系，因此用被动式。

不定式的被动式是个比较复杂的问题。尤其是当不定式同形容词配合使用时很容易造成理解上的困难。下列句子中的不定式通常不用被动式。

① The question is difficult to answer.

② The shirt is too small to wear.

③ I find English easy to learn .

①、②两句中的不定式短语都可以加入逻辑主语，如for me一类，③句中不定式的逻辑主语就是句子的主语。

4.不定式与疑问词连用: what (where, when, how ….) to do

不定式与疑问词连用，其作用相当于一个名词性从句，可充当句子的主语、宾语和表语。

（1) I’m not sure whether to go to the one about accidents.

（2) How to get rid of waste is a great problem for the world today.

（3) The problem is how to feed a growing world population of over 6 billion.

（4) As soon as the reporters know what to write about, they get down to work.

5.不定式做定语时的被动问题

不定式做定语时是否使用被动，是一个十分复杂的问题。简单的判断方法是看句子中是否有不定式的逻辑主语：如果有就用主动式；反之，如果没有不定式的逻辑主语，就用被动式。例如：

The action to be taken is correct.

下列试题的意图便是考查这个问题。

--Have you got anything ______ there?

--No, I will go there myself. Thank you just the same.

A. to be taken B. been taken C. taken D. to take

6.不定式的逻辑主语问题

不定式的逻辑主语表示不定式动作的执行者，通常由介词for加名词、名词性词组或宾格代词构成，置于不定式符号to之前。

（1) Lincoln said that it was not right for the South to break away from the Union.

（2) It was easy for them to carry a guitar on their travel.

在“It is 形容词”结构的句子中，不定式的逻辑主语可能用介词for ,也可能用介词of。当这个形容词同不定式的逻辑主语构成逻辑上的主表关系时，介词用of，否则就用for。

① It is very kind of you to give me so much help.

= You are very kind to give me so much help.（不定式的逻辑主语you可以同形容词kind构成逻辑上的主表关系，介词用of）

② It is important for us to learn English well.

不定式的逻辑主语us不能同important构成逻辑上的主表关系，因此用for。

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