动词不定式是由“不定式符号to+动词原形”构成的一种非谓语动词结构。有些动词不定式不带to，动词不定式可以作句子的主语、表语、宾语、定语、补语、状语或单独使用。不定式保留动词的某些特性，可以有自己的宾语、状语等。动词不定式和它后面的宾语、状语等一起构成短语，叫作不定式短语。
一、用作主语
直接把动词不定式置于句首的情况不多，多数情况用it作形式主语，把真正的主语——动词不定式置于句末，特别是不定式短语较长时。动词不定式作主语，谓语动词用第三人称单数形式。带疑问词的不定式短语作主语常置于句首，复合不定式结构作主语常置于句末。如：
1. I t is our duty to try our best to deal with these problems.
2.The head teacher said it was necessary to talk with his mother.
3.How to learn English well is important.
4.To see is to believe.(眼见为实；百闻不如一见)
二、用作表语
动词不定式作表语，常说明主语的内容、性质、特征。如：
1.The best way is to join an English club.
2.The first thing is to listen to the teacher carefully.
三、用作宾语
1.可以接带to的动词不定式作宾语的动词主要有：要求选择同意(ask, choose, agree)，期望决定学习(expect, hope, decide, learn)，宁可假装知道(prefer, pretend, know)，希望想要愿意(wish, want, would like / love)。如：
1)We decided to talk to some students about why they go there.
2)He prefers to eat white bread and rice.
3)Id love to visit Mexico.
2.动词decide, know, learn, show, teach, tell...，介词结构on...可用疑问词带to的不定式短语作宾语，但why后面的不定式不带to。如：
1)Could you please tell me where to park my car?
2)It gives advice on what to do in lots of different situations.
3.动词feel, find, make, think等后面，可以用it作形式宾语代替真正的宾语——动词不定式，句子结构是...feel / find / make / ... it+adj. / n.+to do...。如：
I find it difficult to remember everything.
4.既可接动词不定式又可接ving形式作宾语，意思差别不太大的动词有begin, start, like, love等。一般说来，动词不定式表一次、数次的具体动作、将来动作或动作的全过程，ving形式表习惯性的连续动作。但是这种区别并不很严格，特别是美国英语，即使是习惯性的动作也可以用动词不定式。如：
1)Then I started to watch Tv.
2)I’m beginning to understand my parents.
begin用了进行时态，后面只接不定式作宾语，表示事情刚开始，还要继续下去。
3)I like to eat vegetables.
感知动词like, love, know等一般不用进行时态。
5.后接动词不定式或ving形式作宾语，意思差别较大的动词有forget, remember等。后接不定式作宾语，表动作尚未发生；后接ving形式作宾语，表动作已经发生。stop to do停下来做另外一件事，to do是目的状语；stop doing停止做、不做当前这件事，doing是宾语。try to do尽力做，try doing试试看；go on to do接着做另外的事，go on doing继续做原来的事。如：
1)When I left home, I forgot to bring it with me.
2)I stopped using them last year.
四、用作定语
1.句子的主语或宾语是动词不定式的逻辑主语，不定式与其所修饰的名词、代词等存在逻辑的动宾关系.
1)I have so many clothes to wash today.
2)I can’t think of any good advice to give her.
3)We have no houses to live in.
2.动词不定式所修饰的名词是place, time, way等时，不定式与这些名词呈现出动状关系或同位关系。如：1)He needs time to do homework.
2) He wants to know the best way to travel around the city.
3.在“there be...”句型里，句子的主语是动词不定式动作的对象：
1)There’s just so much to see and do here.
2)... but there are still many things to do there.
五、用作宾语补足语
1.带to的动词不定式作宾语补足语的动词主要有：要求允许提议(ask, allow, , advise)，期望邀请鼓励(expect, , invite, encourage)，教导告诉想要(teach, tell, want)，等待希望愿意(wait for, wish, would like / love)。如：
1)Id invite her to have dinner at my house.
2 We should allow the children to choose their own clothes.
2.动词不定式作补语，在主动语态句里不带to，被动语态句里带to时多数动词是感官动词和使役动词，包括四“看”：look at, observe, see, watch，三“让”：have, let, make，二“听”：hear, listen to，一“感觉”：feel，一“注意”：notice。如：
1)This picture makes me feel excited！
2)We saw Liu Yu play baseball last week.
3.help后接动词不定式作补语，to可带可不带。
1) they can help you to learn English.
2)Using email English helps you write quickly.
六、用作状语
1.目的状语，置于句首或句末，置于句首时常表示强调。如：
1)In order to catch the early bus, she got up very early.
2)A group of young people got together to discuss this question.
3)She came to this city to visit her daughter.
2.原因状语，多见于“sb.+be+adj.+to do...”结构句中。如：
1) I feel very lucky to have him.
2) he ran out of money to buy old bikes.
3.结果状语，多见于“too...to”，“enough to...”结构句中。如：
1) I’m too tired to do it well.
2)The room is big enough for three people to live in.
七、动词不定式的复合结构
动词不定式的复合结构是“for / of sb. to do sth.”，for / of引出不定式动作的逻辑主语。这种结构在句子中可以作主语、宾语、表语、定语、状语等。不定式复合结构的介词用for还是of，主要决定于前面形容词的性质。一般说来，of前面的形容词是careful, clever, foolish, good, kind, nice, wise等，既说明人的特性，又说明不定式动作的特性。for前面的形容词是dangerous, difficult, easy, hard, heavy, important, interesting, necessary等，一般说明不定式动作的特性，前面如果是名词用for。如：
1.It’s a good idea for parents to allow children to study in groups during the evening.
2.It’s wise of him to do it well.
3)Is it interesting for the baby to play with a pet dog?
八、带疑问词的不定式短语
动词不定式前面可以带疑问代词what, which, who或疑问副词how, when, where, why等。这种结构起名词的作用，在句子里用作宾语、主语、表语等，或者单独使用。要注意的是，why后面的不定式不带to。如：
1.用作句子的成分。
1)I don’t know what to try next. (作宾语)
2)Where to go is not decided yet.(作主语)
2.单独使用时相当于一个特殊疑问句。
1)What to do next?(=What will we / you do next?
2)Why go there?(=Why do we / you go there?
九、动词不定式的否定式
不定式的否定式是not / never to do...，不带to的不定式的否定式是not / never do...如：
1.They decide not to talk to each other.
2.His parents tell him never to play soccer in the street.
单项选择：
（ ）1. The teacher told them ________ make so much noise.
A. don’t B. not C. will not D. not to
（ ）2. My mother often tells me _______so many mistakes.
A. not to make B. to not make C. don’t make D. not make
（ ）3. Tell him _______ the window.
A. to shut (关)not B. not to shut C. to not shut D. not shut
（ ）4. The boy wanted to ride his bicycle in the street, but his mother told him ______.
A. not to B. not to do C. not do it D. do not to
（ ）5. Mrs Smith warned(警告) her daughter ________ after drinking.
A. never to drive B. to never drive
C. never driving D. never drive
（ ） 6. The doctor asked the patient ____rich food after the operation(手术).
A. to eat not B. eating not C. not to eat D. not eating
（ ）7. The workers want us ________ together with them.
A. work B. working C. to work D. worked
（ ）8. I saw him _______ out of the room.
A. go B. went C.is going D. goes
（ ）9. He often makes his little sister _____,
A. cry B. crying C. cried D. to cry
（ ）10 There’re so many kinds of new bikes on sale that I can’t make up my mind _____ to buy.
A. what B. which C. how D. where
（ ）11. He can’t decide ______ to stay or not.
A. whether B. if C. either D. if he will
（ ）12. --- The light in the office is still on. --- Oh, I forgot _______.
A. turning it off B. turn it off
C. to turn it off D. turned it off
（ ）13. We agreed _________ here.
A. met B. meeting C. to meet D. meet
（ ）14. Frank is the kind of person who people like to ________.
A. make friend with B. make friends of
C. make friends D. make friends with
（ ）15. Go on ________ the other exercise after you finishthis one.
A. to do B. doing C.does D. did
（ ）16. She reached the top of the hill and stopped _______ on a big rock
A. rested B. resting C. to rest D. rest
（ ）17. Tom kept quiet about the accident because he was afraid of____ his job. A. lose B. to lose C. losing D. lost
（ ）18. I need a day or two ________.
A. to think it over B. to think over C. of thinking
（ ）19. He was too excited _________.
A. speak B. to speak C. not to speak D. speaking
（ ） 20. I’m hungry. Get me something _________.
A. eat B. to eat C. eating D. for eating
（ ）21. --- I usually go there by train.
--- Why not _______ by boat for a change ?
A. to try going B. trying to go
C. to try and go D. try going
（ ）22. I asked him to _______ me a few minutes so that we could go over all the problems.
A. spend B. spare C. save D. share
（ ）23. They won’t let his mother _______him in that way.
A. to treat B. treated C. treat D. treats
（ ）24. I’m sorry I forgot ______your dictionary. Let’s borrow one from Li Ming. A. to take B. taking C. to bring D. bringing
（ ） 25. She couldn’t decide which restaurant _______.
A. to have lunch B. to eat
C. to eat at D. eating at
（ ） 26. Don’t forget _________ the letter .
A. to send B. send C. sending D. sent
（ ）27. The chair looks very old, I want a new one _________ .
A. sit B.to sit on C. sat D.sit on
（ ）28. Is ______ necessary to return the book tomorrow ?
A. this B. that C. it D. which
（ ）29. I’m afraid they would not allow（允许） him ________ here .
A. to smoke B. smoking C. smokes D. smoke
（ ）30. Mother told me ________ the water before I drank it .
A. boiling B. boiled C. boil D. to boil
（ ）31. On my way home , I stopped _______ some food .
A. buy B. to buy C. buying D. bought
（ ）32. He made John _______ the car for a week as a punishment(惩罚) .
A. to wash B. washing C. wash D.are washing
（ ）33. He needs _______his bedroom ,because it’s too dirty.
A. clean B. cleaning
C. to clean D. cleaned
（ ）34. The first thing is __________ .
A. visit to him B. to visit him
C. visiting him D. visited him
（ ）35. Li Yang advised me _________ too much.
A. not to drink B. to drink
C. not drinking D. drinking
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