(完整版)不定式的用法

不定式的用法

不定式作主语：

To talk with him is a great pleasure.

代替.

一般情况下，不定式（短语）作主语时，通常用形式主语“it”　

It is a great pleasure to talk with him.

的句型。另外，但是，用不定式作主语的句子中还有一个不定式作表语时，不能用It is… to…

这样的句子，不能用动名词作表语。例如：

To see is to believe. (主表一致)

不定式作表语：不定式作表语时常常表将来

不定式可放在be动词后面，形成表语。例如：

My work is to clean the room every day. 我的工作是每天清扫房间。

His dream is to be a doctor.

他的梦想是成为一名医生。

不定式作宾语：

不定式作宾语的动词常见的有：want; hope; wish; ask; choose; decide; manage; offer; promise; refuse; seek; pretend; learn; afford; need…

不定式作宾语的形容词常见的有：ready; eager; sure; glad; anxious; sorry; afraid; free; pleased; willing等

注意:

此外还要注意一些特殊疑问词+不定式的形式（如：what to do, where to go ），作tell, ask, know, show等动词的宾语。

I don’t know what to do.

不定式作宾语补足语：

I asked him to come to my office.

注意:

1) 有些有动词+宾语+不定式的结构，不定式的动词往往be，不定式一般可以省去。例如：consider; find; believe; think; declare（声称）; appoint; guess; fancy（设想）; judge; imagine; know 例如：

We believe him (to be) guilty. 我们相信他是有罪的。

We know him to be a fool. 我们知道他是个笨蛋。（to be 不能省去）

2) 有些动词可以跟there +to be的结构。例如：

believe; expect; intend; like; love; mean; prefer; want; wish; understand等例如：

We didn't expect there to be so many people there.

我们没料到会有那么多人在那里。

3) 注意不定式的省略

①hear, see, watch, notice等感官动词后的省略

②have, let, make三个使役动词后的省略

这两类省略的不定式一旦变成被动语态，不定式要补充完整.

I saw him steal the wallet.

He was seen to steal the wallet.

4) 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。

She could do nothing but cry.

I have no choice but to go.

不定式作定语：

不定式做定语通常要放在被修饰的词后，往往表示未发生的动作。例如：

I have a lot of work to do.我有许多事要做。

There was nothing to bring home that morning. 那天早上（他回家时）两手空空。

其他常考的形式还有chance, opportunity, way,time, the only和序数词及类似序数词的词( 如the last )及there be 句型。

The chance to survive is very limited.

He is the first to come and the last to go.

There is no one to talk with.

不定式作状语：

1) 目的状语(in order to, so as to) He ran so fast as to catch the first bus.

2) 结果状语He hurried to the school to find nobody there.

3) 原因状语We were very excited to hear the news.

4) 条件状语To look at him, you would like him.

注意：

1) 注意不定式的时态

I want to see the film tonight.

When the teacher entered the room, he pretended to be reading English.

Tell your mother the truth, your mother seems to have known the secret.

She is known to have been working on the problem for many years.

强调人的品质

2) It is/was +adj. + of sb. to do…

It is +adj.+ for sb. +to do…强调事物的性质

It is kind of you to help me.

It is easy to learn English well.

3) 不定式的否定式通常在不定式标志to前加上not。例如：

Tell him not to shut the window。

让他别关窗。

4) 不定式的特殊句型too…to…　

a. too…to太…以至于…

b. 如在too前有否定词，则整个句子用否定词表达肯定，too 后那个词表达一种委婉含义，意为"不太"。

It's never too late to mend.

c. 当too 前面有only, all, but时，意思是：非常…　等于very。例如：

I'm only too pleased to be able to help you.

5) 不定式的省略

当不定式在某些词后充当成分时，常可省略动词原形，但要保留不定式的符号“to”

-- Would you like to go shopping with me? -- Yes, I’d like to.

6) 不定式使用中以主动表被动的情况:

在充当定语的情况下Do you have something to eat?

在形容词之后It is easy to learn English.

在被修饰词后(通常表将来)

I need a room to live in.

I have got a letter to write.