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高中英语语法:不定式

不定式一、不定式构成与形式不定式由不定式符号“to”+动词原形构成(有时不带to),其否定形式是“ not to do”。不定式前面可以加某...

不定式

一、不定式构成与形式

不定式由不定式符号“to”+动词原形构成(有时不带to),其否定形式是“ not to do”。不定式前面可以加某些疑问代词,如what、who、which,或疑问副词,如when、where、how、why等,构成特殊的不定式短语,如what to do next, how to get there等。不定式的逻辑主语有时用“ for十名词或代词宾格”构成。

不定式的形式有:

主动形式 / 被动形式

一般式 to do / to be done

完成式 to have done / to have been done

进行式 to be doing 

完成进行式 to have been doing 

二、不定式的用法

不定式不能单独作谓语,没有人称和数的变化,具有名词、形容词和副词的特征,而且还保留着动词的特征,因而可以有状语修饰,如果是及物动词,还可以带宾语,从而构成不定式短语。不定式或不定式短语在句中可以作主语、表语、宾语、定语、状语、主语补足语和宾语补足语。

1. 作主语.不定式短语作主语时,往往放在谓语之后,用it作形式主语。例如:

To see is to believe.

It is right to give up smoking. 

2. 作宾语.不定式短语作宾语时,如果还带有宾语补足语。往往把不定式宾语放在宾语补足语之后,而用it作形式宾语。例如:

He wanted to go.

I find it interesting to study work with him.

3. 作宾语补足语.例如:

He asked me to do the work with him.

注意:在 feel,hear,listen to,look at,notice, observe,see,watch,have,let,make等词后的补足语中,不定式不带to.但是这些句子如果变成被动结构时,就必须带 to.例如

I often hear him sing the song.

He is often heard to sing the song.

注意:不定式动词在介词 but,except,besides后面时,如果这些介词之前有行为动词 do的各种形式,那么,这些介词后的不定式不带to,否则要带to。如:

She could do nothing but cry.

What do you like to do besides swim?

I have no choice but to go.

4. 作定语.例如:

I have some books for you to read.

注①作定语的不定式如果是不及物动词,或者不定式所修饰的名词或代词是不定式动作的地点、工具等,不定式后面须有相应的介词。例如:

He is looking for a room to live in.

There is nothing to worry about.

Please give me a knife to cut with.

但是,不定式所修饰的名词如果是time,place或way,不定式后面的介词习惯上要省去。例如:

He had no money and no place to live.

注②当作定语的不定式所修饰的名词或代词是不定式动作的承受者时,不定式既可以用主动语态,也可用被动语态,但其含义有所不同。试比较:

A) Have you anything to send?

你有什么东西要寄吗?

(不走式 to send的动作执行者是 you)

B) Have you anything to be sent?

你有什么要(我或别人)寄的东西吗?(不定式 to be sent的动作执行者是已被省略的me或someone else)

5. 作状语,表示目的、原因、结果或条件.例如:

I came here to see you.(目的)

We were very excited to hear the news.(原因)

He hurried to the school to find nobody there.(结果)

To look at him, you would like him.(条件)

目的状语还可以用 in order to或 so as to来表示.如:

In order to pass the exam, he worked very hard.

We ran all the way so as not to be late.

不定式也可在作表语用的形容词后面作状语。例如:

I am very glad to hear it.

The question is difficult to answer.

“ too十形容词或副词十不定式”作状语。例如:

He is too old to do that.

另外句子中有 enough这个词时,常用不定式作状语。例如:

The room is big enough to hold us.

6. 作表语.例如:

My job is to help the patient.

7. 作独立成分.例如:

8. 不定式与疑问词 who,which,when,where,how,what等连用,在句中起名词作用,可充当主语、表语、宾语等。例如:

He didn’t know what to say. (宾语)

How to solve the problem is very important.(主语)

My question is when to start. (表语)

注意:在与why连用时,只用于why或why not开头的简短疑问句中,后面紧跟的动词不定式不带to。例如:Why not have a rest? 

9. 不定式在句中用主动式还是被动式。多数情况下是容易判别的,但有时的确比较复杂,请注意以下几点:

A) 不定式修饰的名词或代词和不定式逻辑上构成主谓关系时,不定式往往用主动形式。

Have you got a key to unlock the door? (A key unlocks the door.)

B) 不定式和它前面被修饰的名词或代词构成逻辑上的动宾关系,又和该句主语构成逻辑上的主谓关系时,不定式常用主动形式.

I have got a letter to write.(I write letter.)

He needs a room to live in.(He lives in a room.)

I know what to do.(I do what.)但这句如改为下列形式,不定式就得用被动形式:I know what is to be done.

这是因为 what is to be done是宾语从句,从句中的主语 what是动词 do的动作对象

C) 不定式作表语形容词的状语,和句中主语构成逻辑上的动宾关系时,不定式多用主动形式,这是因为人们往往认为形容词后者去了for one或for people。例如:

He is hard to talk to.(to talk to him)

The book is difficult to understand.( to understand the book)

但如果强调句中的受事者时,亦可用不定式被动式,例如:

The handwriting is very difficult to be read.

The box is too heavy to be lifted.

D) 在there be的结构中,当说话人考虑的是必须有人去完成某件事时,不定式用主动形式,如果说话人强调的是事情本身必须完成,则用被动形式。

There is a lot of work to do.   (Somebody has to do the work.)

There is a lot of work to be done. (The work has to be done.)

请注意下面两个句子的含义是不同的:

There is nothing to do.意为无事可做,感到十分乏味。

There is nothing to be done.意为某东西坏了,无法使之恢复正常。

三、不定式的时态

l) 不定式的一般形式所表示的动作,通常与谓语的动作(状态)同时(或几乎同时)发生,或是在它之后发生。例如:

I saw him go out.

2) 如果谓语表示的动作(情况)发生时,不定式表示的动作正在进行,这时不定式就要用进行式。例如:

I am very glad to be working with you.

3) 如果不定式的动作发生在谓语动词之前,就要用完成式。例如:

I’m sorry to have kept you waiting.

四、不定式的语态

当不定式逻辑上的主语是这个不定式所表示的动作的承受者时,不定式一般要用被动形式。例如:

It is possible for our hopes to be realized.

He was very pleased to have been given such an opportunity.

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