怎么和别人打招呼呢？“Nice to see you.”如何表达自己的愿望呢？“I want to go to America.”。你有没有想过，这些挂在嘴边的话，里面的to是什么呢？就让我们一起来认识它吧。
30.1动词不定式概述
动词不定式是一种活跃的非谓语动词。它在句中起的是名词、形容词或副词的作用，可在句子中作主语、宾语、定语、状语和宾语补足语。动词不定式的形式是“to +动词原形”，但to 有时要省去。
30.2动词不定式的基本用法
（1）动词不定式作主语，例如：
To master a language is not an easy thing.
掌握一门语言不是一件容易的事情。
To persevere means victory.
坚持就是胜利。
动词不定式作主语时可以放在后面，而用 it 作形式主语放在原主语的位置上，这样使句子显得平稳些。例如：
It"s nice not to be dependent on them.
不依靠他们是好的。
It feels good to be out here for a while.
出来在这儿待一会儿是挺舒服的。
如果要说明不定式表示的动作是谁做的，可以在不定式前加一个for引起的短语。例如：
It is a great honor for us to be present at this rally.
我们来参加这个大会是很荣幸的。
It is not hard for one to do a bit of good.
一个人做点好事并不难。
在以某些形容词（如kind， good， nice， wise， clever， silly， wrong， right， foolish， careless，considerate， rude， naughty， impolite 等）作表语时，不定式前常可加一个of 引起的短语，来说明不定式指的是谁的情况。例如：
It is wise of them to turn down the proposal.
他们拒绝这个建议是明智的。
It is very nice of you to be so considerate.
你们想得这样周到是很好的。
（2）动词不定式作宾语，例如：
He promised me never to do it again.
他向我保证再也不做了。
有的及物动词要求跟复合宾语（即宾语+宾语补足语）。如果其中的宾语是不定式短语，则必须将形式宾语it 放在宾语的位置上，而将不定式短语（真正的宾语）放在宾语补足语之前。例如：
I find it useful to learn English well.
我发现学好英语很有用。
We thought it wrong not to tell her.
我们认为不告诉她是错误的。
能以不定式作宾语的动词很多，常见的有 want， like， wish， hate， prefer， hope， continue，manage， try， ask， offer， start， forget， promise， mean， pretend， intend， begin， attempt， decide， learn，desire， agree， care， choose， determine， undertake， expect 等。
另外，tell， advise， show， teach， find out， decide， discuss， learn， forget 等动词常用一个带连接代（副）词的不定式作宾语。例如：
They will teach us how to repair farm tools.
他们将教我们如何修理农具。
We must decide whether to go or stay.
我们得决定去还是留。
（3）动词不定式作表语，例如：
To see is to believe.
眼见为实。
To do this would be to cut the foot to fit the shoe.
这样做是削足适履。
（4）动词不定式作定语。动词不定式作定语，要放在它所修饰的名词或代词的后面。例如：
I have nothing to say on this question.
对这个问题我无可奉告。
She is a very nice person to work with.
她是一个很好共事的人。
（5）动词不定式作状语。动词不定式及其短语具有副词的特性，可在句中用作状语。
① 放在句首也可以放在句尾表示目的、结果等。例如：
No one stopped to help her for the last hour or so.
已差不多一个小时了，没有一个人停下来帮他。
You should eat to live， not live to eat.
吃饭是为了活着，但活着不是为了吃饭。
What have I said to make you so excited？
我说了什么话使你这样激动？
另外，不定式也常用在so as (to) 或 in order (to) 后，与其合起来作状语用，表示目的。
例如：
Let"s hurry so as not to be late for class.
咱们快点走，免得上课迟到。
In order to achieve this goal， we must learn from others.
为了实现这个目标，我们必须向别人学习。
② 跟在作表语的形容词或过去分词的后面。例如：
We are proud to be young people of China.
作为中国的青年我们感到自豪。
We should “not feel ashamed to ask and learn from people below”.
我们要不耻下问。
③ 用在too ...to ...结构中或是带有enough 的句子中。例如：
He is too young to understand all that.
他太年轻了，不能理解这一切。
She was not old enough to understand all that.
她年岁不够大，不能理解这一切。
（6）动词不定式作宾语补足语。很多动词都有这样的用法，常见的动词有ask， tell， invite，compel， force， oblige， get， beg， allow， help， wish， want， expect， encourage， advise， persuade，instruct， permit， remind， request， warn， press， urge 等。例如：
Her mother forbids her to go out.
她妈妈禁止她出去。
What made you think like that？
是什么使你这样想？
Dialogue & Analysis（此处有视频学习资料）M： I go in quietly so as not to disturb the host.（in order， so as+不定式通常用来表示目的，其中so as to 只可用在句中。）There is no time to loose.（不定式一般在名词式代词的后面作修饰语。）I am too hungry to go any farther.（too ...to ...表示“太……而不能……”，不定式用肯定形式表示否定意义。）I want to find something to eat.（不定式一般在名词式代词的后面作修饰语。）I think it right for me to work here.（在“for +名词式代词的宾格+不定式”中，名词式代词的宾格实际上是不定式所表示的动作的逻辑主语。此句中，不定式短语for me to work here 作宾语。）
I consider the host (to be) too lazy（.believe， consider等动词后的不定式主要是to be，to be 常可省略。）I felt it our duty to help others.（用形式宾语it 代替不定式放在谓语的后面，而把真正的作宾语的不定式放在句尾。）
H： It"s careless of me to forget to lock the door.To forgive is divine.（不定式在句中可以充当主语，谓语动词一般要用单数形式。）
Task 1
选择题。
1.Mrs.Smith warned her son after drinking.
A.never to drive
B.to never drive
C.never driving
D.never drive
2.Here isn"t any difference between the two.I really don"t know .
A.where to choose
B.which to choose
C.to choose what
D.to choose which
3.She pretended me when I passed by.
A.not to see
B.not seeing
C.to not see
D.having not seen
4.Ella is the kind of person who people like to .
A.make friend with
B.make friends of
C.make friends
D.make friends with
5.Ben kept quiet about the scandal lose his job.
A.so not as to
B.so as not to
C.so as to not
D.not so as to
30.3动词不定式的时态
（1）不定式的一般形式所表示的动作，通常与主要谓语所表示的动作同时发生，或是在它之后发生。例如：
Tell her we shall be delighted to come.
告诉她我们会很高兴来的。
They invited us to go there this summer.
他们邀请我们今年夏天到那儿去。
进行时形式表示由动词不定式表示的动作与主要动词所表示的动词发生在同一时间。
例如：
You are not supposed to be working.You haven"t quite recovered yet.
你现在不应当工作，你的病还没有完全好呢。
（2）当主要动词是help， see， hear， watch 或 notice 等时，用不定式形式来表示两个动作在同一时间发生。例如：
They saw her clean the room.
他们看见她在打扫房间。
I helped him (to) cross the street.
我帮助他过马路。
（3）与expect， hope， intend， want 等动词的现在时连用时，不定式表示将来的动作。例如：
He expects to go there tomorrow.
他想明天去那儿。
I hope to see you again in a few days.
我希望几天后能再见到你。
（4）不定式的完成时表示所指的动作发生在主要动词表示的动作之前。例如：
I am sorry to have kept you waiting for so long time.
真抱歉让你等了这么久。
（5）如果主要谓语表示的动作发生时，不定式表示的动作正在进行，这时不定式就要用进行时。例如：
They seem to be getting along quite well.
他们似乎相处得很好。
How did you come to be working here？
你是怎么来到这里工作的？
（6）如果不定式表示的是在谓语所表示时间之前一直进行的动作，就要用完成进行式。
例如：
I am happy to have been working with you.
我很愉快和你一起工作。
The struggle was known to have been going on for over 10 years.
据悉这场斗争已进行10 多年了。
（7）然而在很多情况下，动词不定式仅仅指动作而不表示任何时间。例如：
It is easier to talk than to act.
说比做容易。
He likes to study in the library.
他喜欢在图书馆学习。
Task 2
用动词不定式补全下列句子。
1.It was a great achievement（10 个月建成一栋24层的楼）.
2.The teacher decided（不惩罚那些上课迟到的学生）.
3.Mr.Green was wondering（是否去看望在法国的儿子）.
4.He feels it challenging（在这么大一所大学做学生会主席）.
5.He was surprised（在这个山村遇见一个中学同学）.
30.4动词不定式的被动语态
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 an honor for me to be asked to speak here.
我很荣幸被邀请在这里讲话。（做主语）
She preferred to be assigned some heavier work to do.
她宁愿给她些更重的活儿干。（做宾语）
He wanted the letter to be typed at once.
他让把信马上打好。（做复合宾语）
The questions to be answered are on page 30.
需要回答的问题在第30 页上。（做定语）
30.5省略to 的动词不定式
（1）在感官动词see， feel， watch， hear， observe， notice， listen to， look at 等和使役动词let，make， have 等后，要跟不带to 的动词不定式作宾语补足语。但这种句子一旦变成被动结构，to 是不能省略的。例如：
I made them give her the money back.
我让他们把钱还给她。
I didn"t see you come in.
我没看见你进来。
She was often seen to act like that.
人们常常看见她这样做。
（2）有些动词（如help）后面作宾补的不定式可以带to，也可以不带to。例如：
Help me get some salt.
帮我拿些盐。
（3）在rather than， other than， would rather， had better， would sooner， had sooner， cannot but，do nothing but (except) 等词组后，to 一般省略。例如：
We had better learn by heart as many sentence patterns as we can.
我们最好尽可能多地学习句型。
It is better to express your anger， rather than bottle it up.
生气宁可发泄出来而不要闷在心中。
（4）在一般的助动词或情态动词（如do， will， shall， would， should， can， may， must 等）后面，to 要省略掉。例如：
- May I come in？
能进来吗？
- Yes， please.
请进。
注意：在ought 和have 后不能省略to。
（5）有时为了避免重复前面的动词，可以把一个不定式省略掉，单留下一个to。例如：
I shall go if I want to.
如果我想去我就去。
- Do you want to give a speech on this subject？
你想就这个题目给大家谈谈吗？
- I prefer not to.
我想不谈为好。
30.6介词to 与不定式符号to 的区别英语中的不定式是以to do something 的形式出现的，这里的to 是不定式符号，没有实际意义。然而，一些动词与介词to 搭配构成短语，从形式上看，与不定式很相似，但是这里的to 后面应该接动名词短语，如look forward to， be accustomed to， get down to， object to， devote oneself/sth.to， contribute to， adapt oneself to， be opposed to， be addicted to 等。例如：
We"re looking forward to seeing you very soon.
我们希望能很快见到你。
He is addicted to drinking/smoking.
杰克嗜好喝酒/吸烟。
He adapted (himself) to living on his own quickly.
他很快就适应了独立生活。
因此，我们要在学习中要不断积累并记忆此类词组。
30.7不定式的特殊句型
1.too … to …（1）“too … to …”意为“太……以至于……”。例如：
He is too excited to speak.
他太激动了，以至于说不出话来。
（2）如在too 前有否定词，则整个句子用否定词表达肯定，too 后的那个词表达一种委婉含义，意为“不太”。例如：
It"s never too late to mend.
改过不嫌晚。（谚语）
（3）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.
能帮助你我非常高兴。
He was but too eager to get home.
他非常想回家。
2.so as to
（1）表示目的，其否定式是so as not to do。例如：
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.
轻点儿进去，别惊醒了婴儿。
（2）表示结果。例如：
Would you be so kind as to tell me the time？
劳驾，现在几点了？
Dialogue & Analysis（此处有视频学习资料）
M： I"m glad to see you.（不定式的简单形式由“to+动词原形”构成，其动作与主要动词同时发生。在本句中，谓语am glad 的状态与see you 发生的时间几乎相同。）
W： Glad to see you， too.What are you doing here？
M： I will get money back from Tom.He promised to raise money for us.（to raise money for us 发生在主要动词promise 所表示的动作之后。）What are you doing here， Jane？
W： I come here to visit my fiancé.Tom promised to marry me.The evidence is not far to seek.（seek， blame 的不定式常常用主动形式表被动意义。）
M： He must pretend to be sleeping.（不定式的进行时由“to+be+现在分词”构成，表示在主要动词的动作发生时，不定式的动作正在进行。）
T： I am sorry to have kept you waiting for long.（不定式的完成时由“to+have+过去分词”构成，表示不定式的动作发生在主要动词的动作之前。）
M： I will wait as long as I can get the money back.
T： Oh， I have a meeting to prepare.As to the money， how about tomorrow？
M： We really need the money.Please give me today.
T： But the meeting to be held tomorrow is very important.（不定式的被动语态的基本形式是：to+be+过去分词。）
W： Peter， you have so much money.Give a little to John.OK？
T： My firm went into bankruptcy.Even my house is to let.（let 的不定式多用主动形式表示被动含义，但如果后面接修饰语时，则通常用被动形式。）
W： You are a liar.I hate to have been treated like that.（to have been treated 是不定式的完成时的被动形式。）
R
ole Play
Watch the video one more time， try to imitate the dialogue with your partners， and then， show your performance to your classmates.
Task 3
选择题。
1.I saw him out of the room.
A.go
B.had gone
C.has gone
D.goes
2.My mother is sleeping.You"d better .
A.not wake her up
B.not to wake her up
C.not wake up her
D.not to wake up her
3.I"ve heard him about you often.
A.spoke
B.speaks
C.speak
D spoken
4.Though he had often made his little sister ， today he was made by his little sister.
A.cry；to cry
B.crying；crying
C.cry；cry
D.to cry；cry
5.I prefer rather than .
A.read；watch
B.to read；watch
C.reading；to watch
D.to read；to watch
Let"s Say
口头练习：在下列各句中，用所给的动词带一个不定式短语来转述某人的话。
allow remind order warn advise force require permit Example： The professor said to Alan， “You may leave early.”
The professor allowed Alan to leave early.
Alan was allowed to leave early.
1.The general said to the soldiers， “Surround the enemy！”
______________________________________________________________________________
2.Bob said to me， “Don"t forget to take your book back to the library.”
______________________________________________________________________________
3.Paul thinks I have a good voice， so he said to me， “You should take singing lessons.”
______________________________________________________________________________
4.Mrs.Anderson was very stern and a little angry.She shook her finger at the children and said to them， “Don"t play with matches！”
______________________________________________________________________________
5.I am very relieved because the Dean of Admissions said to me， “You may register for school late.”
______________________________________________________________________________
选择题。
1.It"s kind you to help me do the homework.It"s hard me to finish it.
A.of；for
B.for；of
C.of；to
D.for；for
2.They knew her very well.They had seen her up from childhood.
A.grow
B.grew
C.was growing
D.to grow
3.The chair looks rather hard， but in fact it is very comfortable to .
A.sit
B.sit on
C.be sit
D.be sat on
4.Last summer I took a course on .
A.how to make dresses
B.how dresses be made
C.how to be made dresses
D.how dresses to be made
5.We agreed here but so far she hasn"t turned up yet.
A.having met
B.meeting
C.to meet
D.to have met
6.Tom kept practicing fail the driving test.
A.so not as to
B.so as not to
C.so as to not
D.not so as to
7.Rather than on a crowded bus， he always prefers a bicycle.
A.ride；ride
B.riding；ride
C.ride；to ride
D.to ride；riding
8.This problem is said three times.
A.to have been talked
B.to have discussed
C.having been discussed
D.to have been talked about
9.John， you must get your room after breakfast.
A.to be cleaned
B.to clean
C.cleaning
D.cleaned
10.She did nothing at the photo.
A.except look
B.but to look
C.except to look
D.but looking
11.I feel it an honor to speak here.
A.to be asked
B.to ask
C.having asked
D.asked
12.this cake， you"ll need 2eggs， 175g sugar， and 175g flour.
A.Having made，
B.Make
C.To make
D.Making
13.With the plane in ten minutes， all the passengers on board were asked to turn off their mobile phones.
A.taken off
B.taking off
C.to take off
D.would take off
14.Zhou Lan doesn"t have to be made .She always studies very hard.
A.learn
B.to learn
C.learning
D.learned
15.- Will you have anybody the flowers？
- Yes， I"ll have the flowers .
A.plant；planted
B.to plant；planted
C.plant；to be planted
D.to plant；plant Fun Time
Do You Know How to Swim？
Once a learned man was crossing a river， wishing to enjoy himself.He began to talk to aboatman.
“Do you know mathematics？” he asked.
“No， sir，” replied the boatman.
“Then you have lost one quarter of your life，” said the learned man.“Do you know history？”
“No， sir，” answered the boatman.
“Then you have lost half of your life，” said the scholar.
“Do you know philosophy？” he said.
“I don"t know that， either，” said the boatman.
“Then you have lost three quarters of your life.”
Just then a sudden wind turned the boat upside down.
“Do you know how to swim？” asked the boatman.
“No， no，” replied the man of great learning.
“Well then，” replied the boatman.“You have lost your whole life.”