动词不定式

动词不定式
一. 定义：
动词不定式是非谓语动词的一种，它没有人称和数的变化，在句子中不能独立作谓语，但它仍保持动词的特点，既可以有自己的宾语和状语。

同时动词不定式又具有名词、形容词、副词的特征，在句中可以作主语、表语、宾语、宾语补足语、定语和状语。

二. 动词不定式的构成：to+动词原形
三. 动词不定式作宾语
后面能接不定式作宾语的动词有：agree, ask, choose, decide, forget, hope, learn, want, wish, would like等。

We hope to get there before dark. 我们希望天黑以前到那儿。

The girl decided to do it herself. 那个姑娘决定自己做那件事。

动词不定式作宾语的注意事项（2点）
1. 有些动词既可跟不定式作宾语，也可跟动名词作宾语，但含义不同：
remember to do记住要做某事
remember doing记得曾经做过某事
forget to do忘记要做某事
forget doing忘记曾经做过某事
stop to do停下来去做某事
stop doing停止做某事
go on to do继续做另一件事
go on doing继续做原来在做的事
I remember seeing you somewhere before.
我记得以前在哪儿见过你。

Please remember to turn off the light when you leave.
离开时请记得关好灯。

2. 不定式作宾语时，如带有宾语补足语，则要把不定式放到后面，用it作形式宾语，构成“主语+动词+it+宾补（形容词、名词）+不定式”结构。

如：He found it very difficult to get to sleep.
他发现很难入睡。

四. 动词不定式作宾语补足语
1. 后面能接to不定式作宾语补足语的动词有：ask, order, teach, tell, want, wish, help等。

The teacher told us to do Exercise 1. 老师要我们做练习一。

I want both of you to go. 我要你们俩去。

We helped her (to) repair her bike. 我们帮助她修理自行车。

2. 使役动词let, have, make及感官动词see, watch, notice, hear, feel等要以不带to的不定式作宾补。

Let’s have a rest. 我们休息一会吧。

I saw him come in. 我看见他进来了。

感官动词后既可跟不带to的不定式作宾补，也可跟v-ing作宾补，前者表示动作的全部过程已结束；后者表示动作正在进行。

I saw him come downstairs.我看见他下了楼。

（说明他下楼了这件事）
I saw him coming downstairs.我看见他在下楼。

（说明他下楼时的情景）
五. 动词不定式作状语
Later he left home to work in different cities. 不久他离开家到不同的城市工作。

He went to see a football match. 他去看足球比赛了。

In order to catch the other students, I must work hard.
为了赶上其他同学，我必须努力学习。

六. 动词不定式作定语
不定式作定语一般放在所修饰的词的后面。

I need something to eat.
Do you have something to read?
Tom was so excited that he had no word to say.
He is really a fool only to eat.
The man to stand here just now is our English teacher.
The doctor had no way to save the patient.
注意：
（1）作定语的不定式是由及物动词组成，被修饰的名词或代词与不定式之间存在方位或方式关系需要有介词。

I am looking for a room to live in. 我正在找一间住房。

（方位关系）
We have many things to do experiments with.
我们有许多做实验的东西（方式关系）
（2）作定语的不定式是由“be + adj + prep”构成的动词短语。

Here there isn’t any book for me to be interested in.
We have done many things to proud of. 我们做了许多引以自豪的事。

七. 动词不定式作主语
To give is better than to receive.
To reach there on foot is impossible.
动词不定式作主语时，可以用it 代替，把实际主语不定式放在后面。

It’s better to give than to receive.
It’s impossible to reach there on foot.
It’s + adj + for sb. to do sth.
It’s not difficult for me to study English well.
It’s easy for him to work out this math problem.
在这个句型中，如果形容词与不定式的逻辑主语关系密切，并且形容词用来说明逻辑主语的性质、品质、特点等，由of引出逻辑主语。

这类形容词主要有nice, kind, good, wrong, right 等。

八. 动词不定式和疑问词连用
动词不定式可以和疑问词what, which, how, where, when连用，构成不定式短语，可以作主语、宾语、表语、宾语补足语等。

How to do is still a question.
Have you decided when to leave?
九. 动词不定式的否定形式
动词不定式的否定式是在to前加not；不带to的不定式则在动词前加not. 如：
Zhang Ming asked me not to stay at home all day. 张明要我不要整天呆在家里。

My mother let me not do it by myself. 妈妈让我不要独自做这件事。

虚拟语气
虚拟语气是说话人为表示一种假设的情况或一种主观的愿望，即认为动词所表示的动作或状态并非事实或主观设想时所用的语气。

虚拟语气的形式与用法：
1．有一类虚拟语气的形式称为be型虚拟式，即不管主语是什么人称，动词一律用原形(或should+动词原形)。

以下几种情况必须用be型虚拟式：
1)一些表示命令，要求，决定，建议等概念的动词后由that引导的宾语从句中，必须用be型虚拟式。

这类动词有：ask (要求)，advise(建议)，command (命令)，decide (决定)，demand (命令)，insist (坚持)，move (提议)，order (命令)，propose (提议)，recommend (建议)，request (要求)，require (要求)，suggest (建议)，urge (极力主张)。

例如：We strongly suggest that he (should) be told about it earlier．
The doctor insisted that his patient take it easy for three months．
I require that they come by ten．
I recommended that each competitor receive $100．
The judge ordered that the witness tell the truth．
2)一些表示主张、要求、命令、愿望、建议等概念后的主语从句中，必须用be型虚拟式。

此类词主要有：
It is necessary, essential (重要的)，advisable(应该的)，appropriate(合适的)，desirable (值得的)，fitting (合适的)，important (重要的), imperative (必须的)，obligatory (必须的)，proper (适当的)，strange (奇怪的)，urgent (紧要的)，vital (极重要的) that…；
It is (was, has been) suggested (decided，desired，ordered，proposed，requested) that…例如：
It is highly desirable that a new president be appointed．
It is important that everybody have his health checked yearly．
I think it advisable that he leave soon.
It is decided that you be the first one to do the experiment．
3)一些表示主张、要求、命令等概念的名词后面由that引导的同位语从句中，通常用be型虚拟式。

这类词主要有：advice，command，importance，idea，insistence，motion (提议)，necessity，order，plan，proposal (建议)，recommendation (建议)，request，requirement, resolution (决议)，suggestion，understanding (协议)。

例如：My suggestion is that he be sent to help this group．
4) 在lest，for fear that或in case表示“生怕，以防万一，免得”引导的从句中，从句常常用should。

例如：
He studied day and night，lest he should fail in the test．
We dare not play jokes on him for fear that he should become angry．
Be quiet in case you should wake the baby．
*5)某些表示祝愿、诅咒、禁止等的语句中用be型虚拟式。

例如：
God bless you!
God damn you!
Long live Chairman Mao!
Heaven forbid!
2．下列两种句型，从句总是用一般过去式表示虚拟语气。

1) It is (high) time that (该做……，必须做……)，丛句用一般过去时。

例如：
It is time that he went t o bed now．
It is high time that this wrong spending was checked．
2) would rather, would sooner, had rather这些表示“宁愿”的短语后面的从句中的谓语动词应使用一般过去时表示虚拟语气。

例如：
Don't come today．1 would rather you came tomorrow．
He had rather his children didn’t make so much noise．
I would sooner we had dinner now．
3．If引导的条件状语从句的虚拟语气用法
If引导的从句的虚拟语气主要有三种结构：
1)与现在情况相反：主句谓语用“would／could／might +动词原形”，从句谓浯用“动
词的一般过去式”(be的过去式一律用were)。

例如：
If I had time，I would go with you．
If I were you，I might refuse the engagement．
2)与过去情况相反：主句谓语用"would／could + havedone'’，从句渭语用“动词的过去完成式”。

例如：
If I hadn’t lost my way，I would have caught the last train．
They would have arrived earlier if there had been no storm．
3) 与将来情况相反：主句谓语用"would／could／might +动词原形”，从句谓语用"were to／should+动词原形”。

例如：
If you were to see Mary，what would you tell her?
If I were to do it，I would do it in a different way．
If it should rain tomorrow，I would stay at home．
*4) 省略if的虚拟语气句。

虚拟条件从句中的谓语动词如果是were，should，had等词时，可以省略连词if, 但必须将were，should，had等词移至主浯前形成句子倒装。

例如：
Had he been given some information about it, he could have answered the question．Were you to get up earlier，you wouldn’t be late．
4．Wish后的宾语从句中的虚拟语气用法
动词wish后跟由that引导的宾语从句(that经常被省略)要用虚拟浯气表示一种不可实现的愿望。

1)宾语从句用过去式表示与现在事实相反。

例如：
I wish I had enough time to finish my homework today．
My brother is in Europe on vacation，but I wish he were here with me．
2)宾浯从句用过去完成时表示与过去事实相反。

例如：
I wish 1 had gone to the movies with you last night．
I wish Professor Lee had taught me this equation．
3)宾语从句用“would/could +动词原型”表示一种愿望或要求。

例如：I wish that you would come next time．
She wishes that you could stay here longer．
5．由as if／as though引导的状语从句表示方式时，意思是“好像”，这时从句中的谓语动词应用虚拟语气。

1)状语从句用过去式(be用were的形式)表示与现在的事实相反。

例如：
He treats me as if I were a stranger．
2)状语从句用过去完成式表示与过去的事实相反。

例如：
He talked as if he had been to Australia.
6.介词或介词短语表示虚拟：有时假设的情况并不以条件从句表示出来，而是通过一个介词或介词短语来表示，或通过上下文表示出来。

如but for，but that，with，without，otherwise，on condition (that)，in case of，supposing，on the understanding that等表示让步假设。

例如：
If I hadn’t got your help，I wouldn't have found my present job．
= Without your help，I wouldn't have found my present job．
= But for your help，1 wouldn't have found my present job．
= But that you helped me，I wouldn't have found my present job．
7. 错综虚拟条件句：一般来说，主句和从句的谓语动词形式应前后呼应。

但是有时主句和从句的动作发生的时间不一致，谓语动词的形式应作相应的调整，如：从句用过去虚拟语气，主句用现在虚拟语气(通常可以根据时间状语而定)。

Had it not been for the timely investment from the general public，our company would not be so thriving as it is．
If Paul had receivd six more votes in the last election，he would be our chairman now．If you had studied the problem carefully yesterday，you would not find any difficulty now.
8．此外，还有省略了结果主句的虚拟语气if only结构，一般表示愿望。

if only从句中的时态有三种：V+ed；be用were；情态动词用could／would／might+v。

例如：If only he saw me now! 要是他现在能看到我那该多好!
If only she had not been married! 要是她没有结过婚就好了!
If only the committee would approve the regulations and put them into。