動詞不定式是由“不定式符號to+動詞原形”構成的一種非謂語動詞結構。有些動詞不定式不帶to，動詞不定式可以作句子的主語、表語、賓語、定語、補語、狀語或單獨使用。不定式保留動詞的某些特性，可以有自己的賓語、狀語等。動詞不定式和它后面的賓語、狀語等一起構成短語，叫作不定式短語。
一、用作主語
直接把動詞不定式置于句首的情況不多，多數(shù)情況用it作形式主語，把真正的主語——動詞不定式置于句末，特別是不定式短語較長時。動詞不定式作主語，謂語動詞用第三人稱單數(shù)形式。帶疑問詞的不定式短語作主語常置于句首，復合不定式結構作主語常置于句末。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.(眼見為實；百聞不如一見)
二、用作表語
動詞不定式作表語，常說明主語的內(nèi)容、性質(zhì)、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、用作賓語
1.可以接帶to的動詞不定式作賓語的動詞主要有：要求選擇同意(ask, choose, agree)，期望決定學習(expect, hope, decide, learn)，寧可假裝知道(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.動詞decide, know, learn, show, teach, tell...，介詞結構on...可用疑問詞帶to的不定式短語作賓語，但why后面的不定式不帶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.動詞feel, find, make, think等后面，可以用it作形式賓語代替真正的賓語——動詞不定式，句子結構是...feel / find / make / ... it+adj. / n.+to do...。如：
I find it difficult to remember everything.
4.既可接動詞不定式又可接ving形式作賓語，意思差別不太大的動詞有begin, start, like, love等。一般說來，動詞不定式表一次、數(shù)次的具體動作、將來動作或動作的全過程，ving形式表習慣性的連續(xù)動作。但是這種區(qū)別并不很嚴格，特別是美國英語，即使是習慣性的動作也可以用動詞不定式。如：
1)Then I started to watch Tv.
2)I’m beginning to understand my parents.
begin用了進行時態(tài)，后面只接不定式作賓語，表示事情剛開始，還要繼續(xù)下去。
3)I like to eat vegetables.
感知動詞like, love, know等一般不用進行時態(tài)。
5.后接動詞不定式或ving形式作賓語，意思差別較大的動詞有forget, remember等。后接不定式作賓語，表動作尚未發(fā)生；后接ving形式作賓語，表動作已經(jīng)發(fā)生。stop to do停下來做另外一件事，to do是目的狀語；stop doing停止做、不做當前這件事，doing是賓語。try to do盡力做，try doing試試看；go on to do接著做另外的事，go on doing繼續(xù)做原來的事。如：
1)When I left home, I forgot to bring it with me.
2)I stopped using them last year.
四、用作定語
1.句子的主語或賓語是動詞不定式的邏輯主語，不定式與其所修飾的名詞、代詞等存在邏輯的動賓關系.
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.動詞不定式所修飾的名詞是place, time, way等時，不定式與這些名詞呈現(xiàn)出動狀關系或同位關系。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，句子的主語是動詞不定式動作的對象：
1)There’s just so much to see and do here.
2)... but there are still many things to do there.
五、用作賓語補足語
1.帶to的動詞不定式作賓語補足語的動詞主要有：要求允許提議(ask, allow, , advise)，期望邀請鼓勵(expect, , invite, encourage)，教導告訴想要(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.動詞不定式作補語，在主動語態(tài)句里不帶to，被動語態(tài)句里帶to時多數(shù)動詞是感官動詞和使役動詞，包括四“看”：look at, observe, see, watch，三“讓”：have, let, make，二“聽”：hear, listen to，一“感覺”：feel，一“注意”：notice。如：
1)This picture makes me feel excited！
2)We saw Liu Yu play baseball last week.
3.help后接動詞不定式作補語，to可帶可不帶。
1) they can help you to learn English.
2)Using email English helps you write quickly.
六、用作狀語
1.目的狀語，置于句首或句末，置于句首時常表示強調(diào)。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.原因狀語，多見于“sb.+be+adj.+to do...”結構句中。如：
1) I feel very lucky to have him.
2) he ran out of money to buy old bikes.
3.結果狀語，多見于“too...to”，“enough to...”結構句中。如：
1) I’m too tired to do it well.
2)The room is big enough for three people to live in.
七、動詞不定式的復合結構
動詞不定式的復合結構是“for / of sb. to do sth.”，for / of引出不定式動作的邏輯主語。這種結構在句子中可以作主語、賓語、表語、定語、狀語等。不定式復合結構的介詞用for還是of，主要決定于前面形容詞的性質(zhì)。一般說來，of前面的形容詞是careful, clever, foolish, good, kind, nice, wise等，既說明人的特性，又說明不定式動作的特性。for前面的形容詞是dangerous, difficult, easy, hard, heavy, important, interesting, necessary等，一般說明不定式動作的特性，前面如果是名詞用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、帶疑問詞的不定式短語
動詞不定式前面可以帶疑問代詞what, which, who或疑問副詞how, when, where, why等。這種結構起名詞的作用，在句子里用作賓語、主語、表語等，或者單獨使用。要注意的是，why后面的不定式不帶to。如：
1.用作句子的成分。
1)I don’t know what to try next. (作賓語)
2)Where to go is not decided yet.(作主語)
2.單獨使用時相當于一個特殊疑問句。
1)What to do next?(=What will we / you do next?
2)Why go there?(=Why do we / you go there?
九、動詞不定式的否定式
不定式的否定式是not / never to do...，不帶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.
單項選擇：
（ ）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 (關)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(手術).
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（允許） 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(懲罰) .
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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