动词不定式，为非谓语动词。在英语语法中，动词不定式是指动词中的一种不带词形变化从而不指示人称、数量、时态的一种形式。它之所以被称作不定式，是因为动词不被限定，或者说不被词性变化所局限。不定式属于非谓语动词形式。

对于英语来说接不定式的单词多为“打算”“计划”“希望”“将要做某事”等表示未来（未做的事）的动词。同样与不定式表示不同,现在分词表示正在进行，一般性或经常性发生的行为。

注意manage to do中的动词不定式表示的是已做的事。

语态:动词和参与此动作的主语之间关系的一个术语。当主语是动作的发起者（或之一）时，称为主动语态；

如果动词不定式的逻辑主语是这个不定式所表示的动作的承受者，不定式一般要用被动语态形式。如：

It's a great honour to be invited to Mary's birthday party.（不定式作主语是被动语态to be invited是被邀请）

It was impossible for lost time to be made up.（不定式作主语）

I wish to be sent to work in the country.（不定式作宾语）

Can you tell me which is the car to be repaired?（不定式作定语）

My work is to clean the room every day.（不定式作表语）

在There be结构中，修饰主语的不定式可用被动，也可用主动。如：

There are still many things to take care of (to be taken care of).

但有时两种形式表达的意思不同，如：

There is nothing to do now.( We have nothing to do now.)

There is nothing to be done now.(We can do nothing now.)

(1) 一般式：一般现在时表示的动词，有时与谓语动词表示的动作同时发生，有时发生在谓语动词的动作之后。一般为：动词+ to do something

He seems to know this.

I hope to see you again. = I hope that I'll see you again.　我希望再见到你。

(2) 完成式：表示的动作发生在谓语动词表示的动作之前。

I'm sorry to have given you so much trouble.

He seems to have caught a cold.

(3)进行式：表示动作正在进行，与谓语动词表示的动作同时发生。

He seems to be eating something.

(4)完成进行式：

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

一般在表示情绪的动词后加to do也表将来

疑问词who,what,which,when,where,whether,how后可接不定式构成不定式短语，在句中作主语、宾语、表 语等。如：

①When to leave for London has not been decided yet. （不定式在句子中做主语）

②Mr. Smith didn't know whether to leave or stay there. （不定式在句子中做宾语）

③I asked Professor Xu how to learn English well. （不定式在句子中做直接宾语）

④The question was where to get the medicine needed. （不定式在句子中表语）

以上例句中疑问词+不定式部分，均可转换为相应的从句形式。如：①When we shall leave…③…how I

could learn……

经常在这种结构中使用的动词有：consider,decide,discover,explain,find out,forget,hear,know,lea rn,observe,understand,wonder等。

动词不定式作主语时，句子的谓语动词常用单数，其位置有以下两种：

(1)把不定式置于句首。如：

To get there by bike will take us half an hour.骑自行车到那儿将花费我们半个小时。

To make up for lost time is not possible.要弥补失去的时光是不可能的。

To lean out of the window is dangerous.身子探出窗外很危险。

To save money now seems impossible.现在好像不可能存钱。

(2)用it作形式主语，把真正的主语不定式置于句后，常用于下列句式中。如：

①It+is+名词+to do

It's our duty to take good care of the old.照顾老人是我们的责任。

It is an offence to drop litter in the street.在马路上乱丢废物是违章的。

②It takes sb+some time+to do

How long did it take you to finish the work?你花了多少时间来完成这项工作？

③It+be+形容词+for/of sb+to do

It is difficult for us to finish writing the composition in a quarter of an hour.我们难以在四分之一小时内完成这篇作文。

It is stupid of you to write down everything (that) the teacher says.你把老师说的所有东西都记下来的行为是很愚蠢的。

④It seems(appears)+形容词+to do

It seemed impossible to save money.

在句型③中，常用表示客观情况的形容词，如：difficult,easy,hard,important,impossible,necessary 等；在句型③的第二个例句中，常用careless,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise等 表示赞扬或批评的词。在不定式前的sb，可看作其逻辑主语。这一句式有时相当于Sb be+形容词+to do句式 ，如：It's kind of you to help me with my English.=You are kind to help me with my English.

⑤It + 不定式结构可位于believe/consider/discover/expect/find/think和wonder之后

He thought it would be safer to go by train.他认为乘火车比较安全。

He will find it is hard to make friends.他会感觉到交朋友困难。

⑥不定式的完成式也可作句子的主语

To have made the same mistake twice was unforgivable.两次犯同样的错误是不可原谅的。

It is better to have loved and lost than never to have loved at all.爱过而后失去了爱，比从未爱过要好。

(3)举例

（1） It's easy (for me) to do that.我做这事太容易了

easy,　difficult,　hard,　important,　possible,　impossible,　comfortable,　necessary,　better;

the first,　the next,　the last,　the best,　too much,　too little,　not enough

It's so nice to hear your voice.听到你的声音真高兴。

It's necessary for you to lock the car when you do not use it.当你不用车的时候，锁车是有必要的。

（2） It's very kind of him to help us.　他帮助我们，他真好。

Kind,　nice,　stupid,　rude,　clever,　foolish,　thoughtful,　thoughtless,　brave,　considerate(考虑周到的),　silly,　selfish(自私的)

例句:

It was silly of us to believe him.　我们真愚蠢，竟然相信了他。

It seemed selfish of him not to give them anything.　他不给他们任何东西，这显得太自私了。

注意：（1） 其他系动词如，look，appear等也可用于此句型

（2） 不定式作为句子成分时，动词用单数形式。

（3） 当不定式作主语的句子中又有一个不定式作表语时，不能用It is… to…的句型

(对)To see is to believe.　眼见为实。

(错)It is to believe to see.

(1) 以下动词后，只能跟不定式作宾语

afford （付得起），agree（同意），aim(力求做到)，appear（显得），arrange（安排），attempt （试图），care（想要），choose（决定），claim（声称），condescend（屈尊），consent（准许），decide（决定），demand（要求），determine（决心），endeavor（竭力），expect（期待），fail（未履行），help（帮助），hesitate（犹豫），hope（希望），learn（学会），manage（设法），neglect（疏忽），offer（主动提出），plan（计划），prepare（准备），pretend（假装），proceed（接着做），promise（答应），prove（证明），refuse（拒绝），resolve（解决），seem（觉得好像），swear（发誓），tend（往往会），threaten（预示），undertake（承诺），volunteer（自愿做），vow（发誓），want（想要），wish（希望）

举例：

The driver failed to see the other car in time.

司机没能及时看见另一辆车。

I happen to know the answer to your question.

我碰巧知道你那道问题的答案。

（2） 动词+疑问词+ 不定式

decide,know,consider forget,learn,remember,show,understand,see,wonder,hear,find out,explain,tell

Please show us how to do that. 请演示给我们如何去做。

There are so many kinds of tape-recorders on sale that I can't make up my mind which to buy.有这么多的录音机，我都拿不定主意买哪一种。

注意：疑问词带不定式在句中作成分时，谓语动词用单数。

The question is how to put it into practice.

问题是怎样把它付诸实施。

(3)当复合宾语中的宾语是不定式时，先用形式宾语it代替不定式，把不定式置于补语之后，即：主语+动词+it+补语+to do句式。如：

We think it quite important for us to learn a foreign language well.

He feels it his duty to help the poor.

I find it difficult to learn English well.

(1) 动词+宾语+不定式(to do)

常见动词：advise，allow，believe，cause，challenge，compel，declare，encourage，forbid，force，　find，hire，induce，instruct，invite，like，order，permit，persuade，remind，request，require，select，send，suppose，tell，train，urge

例句：

a.　Father will not allow us to play on the street.

父亲不让我们在街上玩耍。

b.　We believe him to be guilty.

我们相信他是有罪的。

(2) to + be 的不定式结构，作补语的动词。

常见动词：Acknowledge,　believe,　consider,　think,　declare(声称),　discover, fancy(设想),　feel,　find,　guess,　judge,　imagine,　know,　prove,　see(理解), show,　suppose,　take(以为),　understand

We consider Tom to be one of the best students in our class.

我们认为汤姆是班上最好的学生之一。

(3) to be +形容词

常见动词：Seem,　appear,　be said,　be supposed,　be believed,　be thought,　be known,　be reported,　hope, wish,　desire,　want,　plan,　expect,　mean…

The book is believed to be uninteresting.

人们认为这本书没什么意思。

(4)　there be+不定式

常见动词：believe,expect,intend,like,love,mean,prefer,want,wish,undrstand

We didn't expect there to be so many people there.我们没料到会有那么多人在哪里。

有些动词需用as 短语做补语，如regard,think believe,take,consider.

We regard Tom as our best teacher.　我们认为汤姆是我们最好的老师。

Mary took him as her father .　玛丽把他当作自己的父亲。

(5)to be不定式作补语

to be不定式， 即不带“to”的不定式，其语法功能一般在句子中作宾语的补语（宾语补足语）。

用to be不定式作宾语补足语的常用动词如下：

口诀：“五看、三使役“，“两听、一感”要记住，若是“宾补”变“主补”，主补“to”字不能无。动词let属例外，其宾补/主补“to”均无。说明：

五看-----see/watch/notice/observe/look at；三使役-----have/make/let；两听-----hear/listen to；一感-----feel。

例句：I often see him go to school on foot.(to be不定式作宾语补足语) He is often seen to go to school on foot.(不定式作主语补足语，要带“to”) Let him try again.---- He is let try again.(let的主补与宾补均用to be不定式)

Find 后可用分词做宾补，或先加形式宾语，再加形容词，最后加带to 的动词不定式。find后也可带一个从句。此类动词还有get，have。

I found him lying on the ground.

I found it important to learn.

I found that to learn English is important.

不定式作表语表示具体动作或将来动作；动名词作表语表示抽象的一般行为。

①To be kind to the enemy is to be cruel to the people.

②My chief purpose is to point out the difficulties of the matter.

③What I would suggest is to put off the meeting.

当主语和表语都是不定式时，其含义一是条件，一是结果（例①）。当主语是aim,duty,hope,idea,mista ke,plan,purpose,suggestion等为中心词的名词词组（例②）时，或以what引导的名词性分句（例③），不定 式说明主语的内容。

④Our work is serving the people.

⑤What he likes is taking a walk after supper.

⑥The story told by Mr.Wang is interesting.

④⑤句动名词作表语，与主语部分可以转换，如Serving the people is our work,而⑥句中是现在分词作表语，说明主语的性质、状态，现在分词具有形容词的各种特征，另外，动名词作表语还应与进行时态区别开来。

（1）目的状语

To… only to (仅仅为了),　in order to,　so as to,　so(such)… as to… (如此……以便……)

He ran so fast as to catch the first bus.　他飞快地跑以便赶上第一班车。

I come here only to say good-bye to you.　我来仅仅是向你告别。

（2）作结果状语，表事先没有预料到的，要放在句子后面。

What have I said to make you angry.

He searched the room only to find nothing.

（3）表原因

I'm glad to see you.

典型例题

The chair looks rather hard,but in fact it is very comfortable to ___.

A. sit　B. sit on　C. be seat　D. be sat on

答案：B.　如果不定式为不及物动词，其后应有必要的介词。

当动词与介词连用时，常位于“形容词+动词不定式”结构的末尾。

⒈不定式作定语

不定式在句中作定语，置于被修饰的名词或代词之后。如：

①The next train to arrive is from Washington.

②Do you have anything to be taken to your sister?

③Do you have anything to say on the question?

④Would you please give me some paper to write on?

⑤My wish to visit France has come true at last.

不定式短语作定语和被修饰词之间表示以下关系：

(1)表示将来的动作（例①）。

(2)与被修饰词之间有动宾关系，如是不及物动词，则需加介词（例④）。

(3)与被修饰词之间有动宾关系，同时与句中其它词之间又有逻辑上的主谓关系时，尽管有被动含义，却仍 用主动语态（例③）；如只有动宾关系，而无逻辑上的主谓关系，则需用被动语态（例②）。

(4)不定式作定语时，一般可转换为定语从句，例①to arrive=that will arrive。

注意：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，不定式后面需有相应的介词。如：

He found a good house to live in. 他找到了一个居住的好房子。

The child has nothing to worry about. 这个孩子无忧无虑。

What did you open it with? 你用什么打开它？

如果不定式修饰time,place,way，可以省略介词：

He has no place to live. 他无处安身。

This is the best way to work out this problem. 这是解决这个问题的最好办法。

如果不定式所修饰名词是不定式动作承受者，不定式可用主动式也可用被动式：

Have you got anything to send? 你要送什么东西吗？

Have you got anything to be sent? 你有什么东西需要送吗？

如果不定式修饰time,place,way，可以省略介词：

He has no place to live. 他无处安身。

This is the best way to work out this problem. 这是解决这个问题的最好办法。

如果不定式所修饰名词是不定式动作承受者，不定式可用主动式也可用被动式：

Have you got anything to send? 你要送什么东西吗？

Have you got anything to be sent? 你有什么东西需要送吗？

（1）情态动词( 除ought 外，ought to意思是“应该”，是情态动词，只有一种形式，后边接动词不定式，to不能省略。ought to没有人称和数的变化，后接动词原形可以表示现在、将来或过去将来，由时间状语或上下文决定。例如：They ought to come tomorrow.他们明天应当来)：

（2）使役动词let,have,make：

（3）感官动词see,watch,look at,notice,observe,hear,listen to,smell,feel,find 等后作宾补，省略to。

注意：在被动语态中则to 不能省掉。

在使役动词中get除外(get sb. to do sth.)

I saw him dance.

=He was seen to dance.

The boss made them work the whole night.

=They were made to work the whole night.

（4） 表示个人意愿或倾向的would rather，had better，might(just) as well：rather than置于句首时。

Rather than ride on a crowded bus,he always prefers to ride a bike.

（5） Why… / why not…：

（6） help 可带to，也可不带to,help sb (to) do sth：

（7） but和except：but前是动词do时，后面出现的动词用不带to的动词不定式。

（8） 由and,or和than连接的两个不定式，第二个to 可以省去：

（9） 通常在discover,imagine,suppose,think,understand等词后，可以省去to be：

He is supposed (to be) nice.　他应该是个好人。

（10）but作介词（表示除了....以外），后接不定式结构时，前面谓语动词部分若含有do的形式时，but后的不定式要省去to，否则要带to。

He wants to do nothing but go out.

He wants to believe anything but to take the medicine.

（11）当两个或多个不定时短语由连词and，but或or连接时，后一个或几个不定式符号to常省略。但若表示对比、对照关系时，则不能省略。

He wants to move to France and marry the girl.

The purpose of new technologies is to make life easier,not to make it more difficult.

（12）不定式做表语时，一般要带to，但若谓语部分中含有do的各种形式时，符号to可省去。

We've missed the last bus.All we could do nowis walk home.

Tell him not to shut the window…

She pretended not to see me when I passed by. 我走过的时候，她假装没看见。

so as to

（1） 表示目的；它的否定式是so as not to do。

Tom kept quiet about the accident so as not to lose his job.汤姆对事故保持沉默是为了不丢掉他的工作。

Go in quietly so as not to wake the baby.轻点进去，别惊醒了婴儿。

（2）　so kind as to ——劳驾

Would you be so kind as to tell me the time?劳驾，现在几点了。

例如：

Why not take a holiday？

干吗不去度假？

3、It's for sb.和 It's of sb.

（1）for sb. 常用于表示事物的特征特点，表示客观形式的形容词，如easy,hard,difficult,　interesting,impossible等：

It's very hard for him to study two languages. 对他来说学两门外语是很难的。

（2）of sb的句型一般用表示人物的性格，品德，表示主观感情或态度的形容词，如good,kind,nice,clever,foolish,right。

It's very nice of you to help me. 你来帮助我，你真是太好了。

for 与of 的辨别方法：

用介词后面的代词作主语，用介词前边的形容词作表语，造个句子。如果道理上通顺用of，不通则用for。如：

You are nice.　(通顺，所以应用of)。

He is hard.　(人是困难的，不通，因此应用for。)

4、不定式的特殊句型too…to…

（1）too…to　太…以至于…

He is too excited to speak.他太激动了，说不出话来。

——Can I help you 需要我帮忙吗

——Well,I'm afraid the box is too heavy for you to carry it,but thank you all the same.　不用了。这箱子太重，恐怕你搬不动。谢谢您。

（2）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.　(谚语)

改过不嫌晚。

（3）　当too 前面有only,all,but时，意思是：“非常…” 等于very。

I'm only too pleased to be able to help you. 我非常高兴能帮助你。

He was but too eager to get home. 他非常想回家。

to 有两种用法：

一为不定式+动词原形；

一为介词+名词动名词，to 在下面的用法中是第二种，即to+ 名词/动名词：

admit to承认，confess to承认，be accustomed to 习惯于，be used to 习惯于， stick to 坚持， turn to开始，着手于， devote oneself to 献身于，　be devoted to 致力于， look forward to 盼望，pay attention to 注意

介词but,except,besides+to do(do)

在这种句型中，如介词前有动词do，后面应接不带to的不定式；如无do，则接to不定式，即带do不带to， 带to不带do。如：

The enemy soldiers had no choice but to give in.

On Sunday afternoon I had nothing to do but watch TV.

1 动名词与不定式的区别

动名词表达的是：状态，性质，心境，抽象，经常性，已发生的；不定式表达的是：目的，结果，原因，具体，一次性，将发生的。

2 接不定式或动名词，意义相同

3在下列情况下，一般要用不定式：

①hate,like,love前有would(should)时，如：I'd like to have a cup of coffee.

②当谓语动词begin,continue,start等是进行式时，如：The students are starting to work on the difficult maths problem.

③begin,continue,start与know,understand等状态动词连用时，如：I soon began to understand what was happening.

⒋advise,allow,encourage,forbid,permit等动词后接动名词作宾语，或带不定式作宾语补足语。如：

Our teachers don't permit our/us swimming in the lake.

Our teachers don't permit us to swim in the lake.

4 部分动词后接不定式或动名词时，意义差别较大，应根据句子语境选择使用。

①forget,remember,regret后接不定式，表示现在或未来的动作，接动名词表示动作已经发生。如：

Don't forget to post the letter for me.

Have you forgotten meeting her in Beijing Airport?

Remember to close the windows before you leave.

I remember writing him a letter a year ago.

We regret to tell you that all of you are not invited to attend the meeting.

They regretted ordering these books from abroad.

目录

1　stop to do（停现在做的去做另一件事）　stop doing（停止正在做某事）

2 forget to do（忘记去做某事）　forget doing（忘记做了某事）

3　remember to do（记得要去做某事）　remember doing（记得做过某事）

4 regret to do（遗憾做某事）　regret doing（遗憾做了某事）

5　cease to do　cease doing

6 try to do（努力做某事）　try doing（试着做某事）

7　go on to do（继续去做某事）　go on doing（继续做某事）

8 afraid to do（担心做某事）　afraid doing（担心正在做的事）

9　interested to do（对做某事感兴趣）　interested doing（对正在做的感兴趣）

10 mean to do（打算做某事）　mean doing（做某事很有意义）

11 begin/ start to do（开始去做某事）　begin/ start doing（开始做某事）

forget doing/to do

forget to do　忘记要去做某事。　(未做)

forget doing　忘记做过某事。　(已做)

The light in the office is stil on. He forgot to turn it off.办公室的灯还在亮着，他忘记关了。(没有做关灯的动作)

He forgot turning the light off.他忘记他已经关了灯了。　( 已做过关灯的动作)

Don't forget to come tomorrow.别忘了明天来。　(to come动作未做)

remember doing/to do

remember to do 记得去做某事　(未做)

remember doing　记得做过某事　(已做)

Remember to go to the post office after school.记着放学后去趟邮局。

Don't you remember seeing the man before?你不记得以前见过那个人吗？

regret doing/to do

regret to do　对要做的事遗憾。　(未做)

regret doing　对做过的事遗憾、后悔。　(已做)

I regret to have to do this,but I have no choice.我很遗憾必须这样去做，我实在没有办法。

I don't regret telling her what I thought.我不为告诉她我的想法而后悔。

cease doing/to do

cease to do　长时间，甚至永远停做某事。

cease doing　短时停止做某事，以后还会接着做。

That department has ceased to exist forever.那个部门已不复存在。

The girls ceased chatting for a moment when their teacher passed by.姑娘们在老师走过时，停了会聊天。

try doing/to do

try to do　努力，企图做某事。

try doing　试验，试着做某事。

You must try to be more careful.你可要多加小心。

I tried gardening but didn't succeed.我试着种果木花卉，但未成功。

go on doing/to do

go on to do　做了一件事后，接着做另一件事。

go on doing　继续做原来做的事。

After he had finished his maths，he went on to do his physics.做完数学后，他接着去做物理。

Go on doing the other exercise after you have finished this one.作完这个练习后，接着做其他的练习

be afraid doing/to do

be afraid to do　不敢，胆怯去做某事，是主观上的原因不去做，意为“怕”；

be afraid of doing　担心出现doing的状况、结果。doing 是客观上造成的，意为“生怕，恐怕”。

She was afraid to step further in grass because she was afraid of being bitten by a snake.

她生怕被蛇咬着，而不敢在草丛中再走一步。

She was afraid to wake her husband.她不敢去叫醒她丈夫。

She was afraid of waking her husband.她生怕吵醒她丈夫。

be interested in doing/to do

interested to do　对做某事感兴趣，想了解某事。

interested in doing　对某种想法感兴趣，doing 通常为想法。

I shall be interested to know what happens.我很想知道发生了什么事。(想了解)

I'm interested in working in Switzerland. Do you have any idea about that

我对在瑞士工作感兴趣。你想过这事吗?　(一种想法)

mean doing/to do

mean to do　打算、想

mean doing　意味着

I mean to go, but my father would not allow me to.我想去，但是我父亲不肯让我去。

To raise wage means increasing purchasing power.增加工资意味着增加购买力。

begin(start) doing/to do

begin/start to do sth

begin/start doing sth.

（1）　谈及一项长期活动或开始一种习惯时，使用doing.

How old were you when you first started playing the piano你几岁时开始弹钢琴？

（2）begin,start用进行时时，后面动词用不定式to do

I was beginning to get angry。我开始生起气来。

（3）　在attempt, intend, begin, start 后接know, understand,realize这类动词时，常用不定式to

do。

I begin to understand the truth。

我开始明白真相。

（4）　物作主语时

It began to melt.

⒉动词不定式的时态，语态

(1)时态

①一般式：动词不定式一般式表示的动作发生在谓语动词之后，有时表示同时发生.如：

I hope to become a university student this year.(to become发生在hope之后)

We often hear Dick play the piano in the next room.(play和hear同时发生)

②完成式：表示的动作发生在谓语动词所表示的动作之前.如：

I'm sorry to have kept you waiting.

We are too young to have seen the old society.

③进行式：表示的动作与谓语动词同时发生.如：

The teacher happened to be correcting our papers when I came in.

They seemed to be discussing something important.

(2)语态

如果动词不定式的逻辑主语是这个不定式所表示的动作的承受者，不定式一般要用被动语态形式，如：

It's a great honor to be invited to Mary's birthday party.(不定式作主语)

It was impossible for lost time to be made up.(不定式作主语)

I wish to be sent to work in the country.(不定式作宾语)

Can you tell me which is the car to be repaired (不定式作定语)

He went to the hospital to be examined.(不定式作状语)

在There be结构中，修饰主语的不定式可用被动，也可用主动，如：There are still many things to take care of (to be taken care of).但有时两种形式表达的意思不同，如：These is nothing to do now.( We have nothing to do now.) There is nothing to be done now.(We can do nothing now.)

⒊动名词的时态，语态

(1)时态

①一般式：动名词的一般式所表示的动作可以是泛指，也可与谓语动词同时发生，或发生在谓语动作之前或之后，如：

We are interested in collecting stamps.

I shall never forget seeing the Great Wall for the first time.

We are not afraid of dying.

②完成式所表示的动作发生在谓语动词之前，如：

Imagine having traveled on the moon.

We were praised for having finished the work ahead of time.

(2)被动语态

①如果动名词的逻辑主语为动名词所表示的动作的承受者，动名词要用被动语态，动名词的被动语态有一般式与完成式之分，如：

The young man came in without being noticed.

He prided himself on having never been beaten in class.

②有些动词后的动名词用主动形式，但表示被动意义，如：

The bike needs repair.

If a thing is worth doing, it is worth doing well.

⒋在口语中，为避免重复，常用“to”代替不定式结构，有时甚至可以把to省略，如：

①-Did you go to visit the Great Wall

-No, I wanted to, but there wasn't enough time.

②-Would you like to come to a party

-I'd love to.

③-Don't make any mistakes in your homework, will you

-I'll try not to.

④-Try to be back by 12,won't you

-OK, I'll try.

另外，be going to, ought to, used to等也常用于这一结构中。

⒌在why引起的问句中，省略“to”，如：

Why spend such a lot of money

Why not wait for a couple of days

⒍当两个或更多作用相同的不定式并列使用时，只在第一个不定式前加“to”，如：

It's quite necessary for us to read more and have more practice.

⒎“to”在下列短语中是“介词”，后接动名词或名词形式，如：

devote…to, face up to(勇敢地面对), look forward to(盼望), object to(反对), take to(养成习惯，对……感兴趣；开始从事某种活动), be used to(习惯于)等。

形式

to be + 现在分词

He seems to be following us.他好像在跟着我们。

用法

①用于助动词之后

He must be coming by bus.他一定是乘公共汽车来的。

You shouldn't be reading a novel.现在你不应该看小说，你应该看课本。

②用于appear，happen，pretend，seem之后

I happened to be standing next to him when he collapsed.相当于：

It happened that I was standing next to him when he collapsed.他倒下的时候我恰巧站在他身边。

③hope 和promise之后，或agree，arrange，decide，determine/be determined，plan，undertake之后，但用于hope和promise后更常见：

I hope/hoped to be earning my living in a year's time.相当于：

I hope I will/I hoped I would be earning……我希望在一年之内能自食其力。

不定式被动式的用法

不定式到底用主动形式还是被动形式，往往取决于句子的意思，即意思上为主动就用主动形式，意思上为被动就用被动形式：

Did it need to be done so soon? 这事需要这么快就做吗?

She can’t bear to be laughed at. 她受不了被人嘲笑。

There was business to be taken care of. 有生意要人管理。

It remains to be seen whether you are right. 你是否正确，以后见分晓。

There was a lot of rubbish to be got rid of. 有大量垃圾需要扔掉。

不定式完成被动式的用法

不定式的完成被动式表示发生在谓语动作之前的被动动作：

I’m pleased to have been given this opportunity. 给了我这次机会我很高兴。

It’s said to have been built in the Ming dynasty. 据说它是明朝修建的。

表示发生在谓语动作之前的动作

He seems to have caught a cold. 他似乎感冒了。

I hate to have quarreled with her. 我后悔和她吵架了。

I believe it to have been a mistake. 我相信这是一个错误。

You appear to have travelled quite a lot. 你似乎作过多次旅行。

I’m sorry to have given you so much trouble. 对不起给了你这么多麻烦。

It’s said to have been built in the Ming dynasty. 据说它是明朝修建的。

表示在某个给定的时间之前已完成的动作

I hope to have finished the work by now. 我希望现在以前已完成这项工作。

表示过去未曾实现的想法和愿望

I should like to have come earlier. 我本想早点来的。

We were to have been married last year. 我们本来打算去年结婚的。

形式

to have been + 现在分词

He seems to have been spying for both sides.

他似乎一直在为两方面搞秘密情报。

用法

只要用于助动词之后和appear，seem之后，但也可以用在happen，pretend以及believe，know，report，say，understand的被动式之后：

He appears to have been waiting a long time.相当于：

It appears that he has been waiting a long time.

看来他已经等了很久了。

He pretended to have been studying. 相当于：

He pretended that he had been studying.

他假装一直在学习的样子。

在There be句型中的动词不定式：

For example one,There are too much homework to write.

two,There are students writing too much homework.

to-infinitive。莎士比亚在著作哈姆雷特的独白时就大量采用了这类不定式动词。

经常跟在to后形成不定式的动词包括:

例如:

这些有宾词，然后加上有to的不定式的动词包括 (连同以上带有星号的动词): advise, allow, challenge, command, compel, condemn, enable, encourage, expect, forbid, force, help, induce, inspire, instruct, invite, oblige, order, permit, persuade, prefer, program, remind, teach, tell, train, urge, warn.

有些动词之后加 for + 宾词 + to-然后不定式. 通常这些动词包含渴望的意思，不能单单在后面加上宾词和不定式 (though an infinitive alone may work). 这些动词包括 apply, arrange, ask, call, clamour, long, opt, plead, press, vote, wait, wish, yearn.

例如:

Infinitives in English exist in many aspects. Here is a table showing these different tenses for the verb to cook.

-er

附在法律用语的动词词根后，表示”……的过程“”……的行为“，源于法语的不定式后缀，动词不定式用如名词。例子有：attainder，detainer，disclaimer，merger，rejoinder，misnomer，ouster，remainder，retainer。

-ure

这一般源于拉丁语名词后缀-ura，但有些源于法语的动词不定式结尾-ir，如pleasure、displeasure、leisure。

ado（名词）源于at do的省略，at是受挪威语影响的不定式记号。much ado开始也是much to do的意思。to-do（名词）则更直接。derring-do（名词）后半部分也是不定式。

affair（名词）来自法语à faire，à相当于介词to，faire（做）也是动词不定式。

拉丁语中以-ere结尾的不定式有些进入古法语后以-re/-ir结尾，进入英语后一般会去掉这个不定式结尾，但有些保留了下来，比如render、bever、surrender、tender、supper、dinner、power。beer有可能是来自拉丁语不定式。

esophagus（食管）来自希腊语oisophagos，前半部分来自pherein（运输，携带）的将来时不定式oisein。

jihad（名词）源于阿拉伯语的不定式。

done的一种方言用法可能与不定式有关。vagary（名词）可能来自拉丁语不定式vagari。

德语动词不定式

在德语中，动词不定式常以-en结尾，如sagen，-en前的部分为动词词干(sag-),但也有少部分以-ern、-n或eln结尾。动词前的zu的用法与英语类似。

作名词

在德语中，动词不定式可以直接用作名词，如das Essen指食物（做名词时，首字母同普通名词一样需要大写）。

作主语

部分德语不定式可用作主语，如anfangen, aufhören, beginnen, andenken, glauben, hoffen, meinen, vergessen, versuchen.

例句：Sie meint, sie hat immer recht -＞ Sie meint, immer recht zu haben- 他认为他总是对的。

荷兰语动词不定式

在荷兰语中，不定式也以-en结尾。在动词前使用te，用法与英语to相似。

如Het is niet moeilijk te begrijpen. -这不难理解。

北日耳曼语（斯堪的纳维亚语支）动词不定式

北日耳曼语动词-n结尾的特征至少在公元前500年就以丢失，-a取而代之。现在的丹麦语和部分挪威语方言以-e作为结尾，东部挪威语多数方言和个别西瑞典语方言则少见-e，多数为-a。

北日耳曼语通常没有类似英语to的词。

西班牙语动词不定式

法语动词不定式