高中英语-不定式用法讲解 精心原创

高中英语动词不定式用法讲解

非谓语之一：不定式to do

一、关于不定式的几个关键问题：

问题1 ：何时用不定式？

----表示要做的事情时。

问题2：不定式能干什么？

---什么都行。谓语除外。

1.To help the poor 主语

to help the poor. 表语

to do. 定语

4. I come here to see you. 状语

to come early. 补语

to help the poor. 宾语

问题3：做不定式的习题应该主语不定式的什么形式变化？

（1）动名词与不定式的区别：

动名词表达的是： 抽象，经常性，已发生的

不定式表达的是： 具体，一次性，将发生的

The heavy rain flooded the village, causing many injuries and deaths.

He hurried to the airport,only to be told that the flight had been cancelled.

（2）有些动词如start,begin,continue,like接不定式或动名词作宾语，意义基本相同。

（3）有些动词如remember,forget,stop接不定式或动名词作宾语，意义大相径庭。

二、不定式相关知识点精讲:

（1）不定式的用法：

①作主语

不定式短语作主语时，可以直接放在句首，但在很多情况下，用先行代词it作形式主语。例如：

To see is to believe. 眼见为实。

It is right to give up smoking．戒烟是对的。

不定式作主语，it作形式主语的常见句型如下：

a. It is + adj (easy, important, difficult…) + 不定式

b. It is + n (a pity, a pleasure, one’s duty, a shame) + 不定式

c. It takes/needs/requires + some time (hours, months, days, patience…) + 不定式

It’s important for us to learn English well. 我们学好英语很重要。

It’s my duty to teach you how to be a useful person. 教你如何做一个有用的人是我的职责。

It requires patience to be a good teacher. 当个好老师需要耐心。

②作宾语

可以直接用不定式作宾语的动词很多，常见的有：agree, afford, tend, ask, decide, determine, expect, fail, hope, learn, intend, manage, offer, plan, promise, refuse, want, wish等。例如：

I offered to help her, but she refused. 我提出帮助她，但她拒绝了。

He pretended not to hear me. 他假装没听见我（的声音）。

③作宾语补足语

常用带不定式作宾补的几种情况：

(a) 主语 + ask / require / tell / order / force / get / want / like + sb.to do sth.

(b)主语 + think / judge / suppose / believe / consider / imagine / consider / feel + sb. + to be/ to have done

(c)主语 + call on / upon / depend on / wait for / ask for + sb.+ to do sth.

例如：

He asked me to do the work with him.他要我与他一起干。

You should get more people to help you.你应该多找些人帮你。

The teacher expected everyone to study hard,老师希望每个人都努力学习。

●注意：

a. 在see，watch，look at，notice, observe，have，let，make, hear，listen to，feel，help等词后的补足语中，不定式不带 to。例如:

I often hear him sing the song．我经常听见他唱这只歌。

The teacher usually made the students recite the text.老师通常让学生背颂课文。

Would you please help me (to) repair my bike?请帮我修理自行车好吗？

但是这些句子如果变成被动结构时, 就必须带 to。例如:

He is often heard to sing the song．人们常听到他唱这只歌。

The students were usually made to recite the text.学生们常被要求背颂课文。

b. 不定式动词在介词 but，except，besides后面时，如果这些介词之前有实意动词 do的各种形式或者情态动词，那么，这些介词后的不定式不带 to，否则要带 to．必背：can do nothing but do =can’t do anything but do=can’t help do but do=can’t choose but do=have no choice to do “只能做，除了......别无选择” 如：

She could do nothing but cry.她只是哭。

What do you like to do besides swim? 除了游泳你还喜欢干什么？

④ 作定语

不定式作定语位于所修饰的名词之后。例如：

I have some books for you to read．我有一些书给你看。

We have a lot of homework to do today.今天我们有很多作业要做。

●注意：a.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．他在找房子住。

There is nothing to worry about．没有什么可担心的。

Please give me a knife to cut with．请给我一把刀用。

但是,不定式所修饰的名词是 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.他没有钱，也没有房子住。

b.比较：

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)

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)

c.下列词语后常接不定式作定语：chance、wish、right、courage、need、promise、time、opportunity、way、the first、the second、the last、the only等。

He is always the first to come and the last to leave.他总是第一个到，最后一个走。

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)我来是看你的。

We were very excited to hear the news．(原因)听到那消息我们很激动。

He hurried to the school to find nobody there．(结果)他匆忙赶到学校，结果发现没有人。

To look at him, you would like him．(条件)如果你见到，你会喜欢他的。

in order (not) to, so as (not) to用来引导目的状语,

其中only to…用于表示意想不到的结果。例如：

The girl was so kind as to help the old man off the bus.那个女孩很热心，帮助老人下车。

In order to pass the exam, he worked very hard．为了通过考试，他刻苦努力学习。

We ran all the way so as not to be late．我们一路跑着，以免迟到。

He is too old to do that．他太老了，不能做那件事了。

The room is big enough to hold us．房间足够大，可以容纳我们。

He hurried to the station only to be told the train had gone.他匆忙赶到车站，结果被告知火车已经开走了。

⑥ 作表语: 位于连系动词之后。

例如：

My job is to help the patient．我的工作是帮助病人。

Our most important task now is to make a plan.我们现在最重要的任务是制定一个计划。

注：作表语的不定式都带to，但当主语部分有实义动词do时，to可以省略。

例如：

The only thing we can do now is wait and see.我们现在唯一能做的事就是等着看。

⑦ 作独立成分。必背：用作独立成分的不定式：

to tell you the truth 说老实话 to be frank 坦率地说 to begin with 首先 to be brief 简言之 to make a long story short 长话短说 to be exact 精确地说 to say nothing of 姑且不说 to conclude 总而言之 to be sure 诚然，固然 to do him justice 说句对他公道的话 so to speak 可以这么说 例如：

To tell the truth，I don’t agree with you.说实话，我不同意你的观点。

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)他不知道说什么。

How to solve the problem is very important．(主语)如何解决问题是非常重要的。

My question is when to start. (表语)我的问题是何时开始。

⑨ 不定式的复合结构 … for / of sb to do sth

for sb. to do sth，这种句式中的常用形容词有：easy, difficult, hard, important, necessary, possible, impossible等。

of sb. to do sth.，这种句式中的常用形容词有：right, wrong, brave, careful, careless, clever, wise, stupid, cruel, foolish, good, honest, kind, nice, silly等。这种复合结构在句中可作主语、表语、宾语、定语、状语等。

判断方法：转化法

It is necessary for me to learn English well.我学好英语十分必要。

It’s difficult for us to master a foreign language.我们掌握一门外语是困难的。

It’s very kind of you to come to see me.你来看我太好了。→You are kind to come to see me.

It’s careless of the boy to make the same mistake again.那个孩子又犯了同样的错误，真是太粗心了。→The boy is careless to make the same mistake again.

⑩ 其他必背结构。

a.常见的带不定式符号to的短语

be supposed to do应该做某事

be determined to do 决心要做某事

fail to do 未能做某事

go all out to do 全力以赴做某事

have the nerve to do 有胆量做某事

have a great mind to do 很想做某事

make a point to do 坚持做某事

make up one's mind to do 决定做某事

take the trouble to do 不辞辛苦地做某事

prepare oneself to do 有思想准备做某事

b.常见的带介词to的短语

be used to 习惯

be equal to 胜任

be given to 沉溺于

be opposed to 反对

be related to与……有关

devote oneself to 献身于

get down to 着手做

give rise to 引起

lead to 导致

look forward to 盼望

object to 反对

pay attention to 注意

put one's mind to 全神贯注于

stick to 坚持