1.It'sour duty _________ the room every day.
A. to clean B. cleaned C. clean D.cleans(甘肃省)
2. It's hard for us _________ English well.
A. learn B. learns C. to learn D.learning(江西省)
It will _________ the workers over a year _________ _________ the flyover.(北京市海淀区)
4.It'svery nice _________ you to get me two tickets _________ the World Cup.
A. for，of B. of，for C. to，for D. of，to(安徽省)
Keys：1. A 2. C 3. take，to，build 4. B
[简析]动词不定式作主语时，可以直接放在谓语动词前面的主语位置，也可以用先行词it作形式主语，而将真正的主语(不定式)置于后面。常见的句式有：(1)It is +形容词(ofsb)to dosth.(2)It is +名词(forsb)to dosth.(3)It takessbsome time to dosth.(4)It is +形容词(forsb)to dosth.句式(1)中常用nice，kind，clever，good，right，wrong，foolish，careless等形容词，与介词of搭配，这些形容词常表述不定式逻辑主语的属性或性质;句式(4)中常用hard，difficult，easy，important等形容词，与介词for搭配，表示不定式表示的动作、行为的性质。
1. He wants ______ some vegetables.
A. buy B. buying C. to buy D. buys (山西省)
2. Don't forget ______ your homework with you when you come to school.
A. to bring B. bringing C. to take D. taking (福建省)
3. He found it very difficult ______.
A. sleeping B.sleepsC.sleptD. to fall asleep (湖南省)
Keys：1. C 2.A 3.D
1. Robert often asks us ______ his Chinese, so his Chinese is much better than before.
A. helphimB. to help him with C. to help with D. helps him with (江苏省)
2.MrLi often teaches his Japanesefriends______ Chinese food.
A. cook B. cooks C. to cook D. cooked (甘肃省)
Key：1. B 2. C
1. She went ______ her teacher.
A. to see B. looks C. saw D. seeing (江西省)
2.Meimeilikes English very much. She does her best ______ English well.
A. learn B. learning C. to learn D. learns (四川省)
Key：1. A 2. C
[简析]go，come，try，do / try one's best等动词或短语动词作谓语时，其后常常可以接不定式作目的状语。
3. I'm sorry ______ that.
A. hears B. hearing C. hear D. to hear (河北省)
4. I'm sorry ______ you.
A. trouble B. to trouble C. troubling D. troubled (吉林省)
5. My mother was very glad ______ her old friend.
A. to meet B. meet C. met D. meets (甘肃省)
Keys：3. D 4.B 5.A
[简析]"be +形容词+ to dosth"结构中的不定式作状语，常表示原因或方式。
6. The panda is so fat that it can't go through the hole.(改为意思相同的句子)
Thehole______ ______ ______ ______ such a fat panda to go through. (广东省)
7. The ice on the lake was so thin that people couldn't skate on it. (改为意思相同的句子)
The ice on the lake wasn't ______ enough ______ people ______ ______ ______. (广东省)
Keys：6. is，too，small，for 7. thick，for，to，skate，on
[简析]在上述"too +形容词/副词(forsb)to do…"(太……而不能……)和"enough (forsb) to do…"(足以、足够……做……)结构中，不定式作结果状语。
1. Would you like something ______?
A. drink B. drinking C. to drink D. drinks (湖北省)
2. I have a lot of homework ______.
A. do B. doing C. did D. to do (河南省)
3. He is not an easy man ______.
A. get on B. to get on C. get on with D. to get on with (山东省)
Key：1. C 2.D 3.D
1. We saw him ______ the building and go upstairs.
A. to enter B. enter C. entering D. entered (河南省)
2. So much work usually makes them ______ very tired.
A. to feel B. feels C. feeling D. feel (吉林省)
3. Your father is sleeping. You'd better ______.
A. not wake up him B. not to wake up him
C. not wake him up D. not to wake him up (陕西省)
4. I was made ______ my homework in the afternoon.
A. do B. doing C. to do D. did (贵州省)
Key：1. B 2.D 3.C 4.C
1.MrBlack asked the man ________ the queue.
A. not to jump B. to not jump C. didn't jump D. not jump (广西壮族自治区)
2. The old man told the child ______ noisy.
A. not be B. not to be C. to not be D. be not (湖北省)
3. There is going to ______ an important meeting tomorrow. Please try ______ late.
A. have，not to be B. have，not be
C. be，not to be D. be，not be (内蒙古自治区)
Key：1. A 2.B 3.C
1. Please stop ______ a rest if you feel tired.
A. to have B. having C. have D. has (广西壮族自治区)
2. ——Whydidn't you buy some bread on your way home?
——Sorry, I forgot ______ some money with me.
A. take B. taking C. to take D. took (湖北省)
3. ——Let'shave a rest, shall we?
——Notnow, I can't stop ______ the letters.
A.writeB. to write C. writing D. and write (湖北省)
4. Jim was badly hurt, so he had to stop ______ (walk). (用所给单词的正确形式填空)(四川省)
Key：1. A 2.C 3.C 4.walking
[简析]一些常见的动词后面接不定式和接动词的-ing形式的区别如下："stop to dosth"意为"停止正在做的事情去做另外一件事"，"stop doingsth"意为"停止正在做的事"："remember to dosth"意为"记住去做某事"(事还未做)，"remember doingsth"意为"记得做过某事"(事已做)："go on to dosth"意为"接着做某事"(做完一事，接着做另一事)，"go on doingsth"意为"继续做某事"(一事未做完接着往下做)："forget to dosth"意为"忘了做某事"(事还未做)，"forget doingsth"意为"忘了曾做过某事"(事已做)。
5. When I was walking in the street I saw a plane ______ over my head.
A. flies B. flying C. flew D. to fly (福建省)
6. A woman saw it ______ when she was walking past.
A. happen B.happensC. happening D. to happen (黑龙江省)
Key：5. B 6. A
1. Would you like to go to the cinema with us?
Yes, ______. What time are we going to meet?
A. I would B. I would like C. I like to D. I'd like to (浙江省)
2. Would you like to go for a picnic with us?
______. What time are we going to meet?
A. No, I can't B. Yes, I'm glad C. Yes, I'd love to D. I'd like (大连市)
Keys：1. D 2. C
[简析]在口语中，动词不定式中的动词或短语动词在上下文中重复出现时，第二个动词不定式可以省略，但是to不可省略。这种用法常见于"be glad to"，"would like (love) to"，"have to"等结构中。
The new hospital ______ is near the factory.
A. build B. builds C. to build D. to be built (青海省)
[简析]当不定式的逻辑主语是不定式所表示的动作的承受者(宾语)时，用动词不定式的被动式，即：to be +过去分词;如果不定式所表示的动作发生在谓语动词表示的动作之前，不定式用完成式，即：to have +过去分词;如果不定式表示的动作和谓语动词表示的动作同时发生，用不定式的进行式，即：to be +现在分词
动词不定式指通常由to加上动词原形 (如to write) 所构成的一种非限定性动词形式，但在有些情况下to可以省略。动词不定式有进行体和完成体(如上to be writing，to have written)，也有被动态(如to be written)，所有的主动词，不论是及物动词还是不及物动词，也不论是动作动词还是状态动词，都有不定式形式。助动词除be和have外, 没有不定式形式。动词不定式在语法功能上可作主语、宾语、表语、定语和状语。
1.Te get contact with his family in Taiwan made him extremely happy since they separated more than 40 years ago．
2.To finish that task in such a short time is really a challenge．
1.It made him extremely happy to get contact with his family in Taiwan since they separated more than 40 years ago．
2.John admitted that it is always difficult for him to be on time．
不定式结构所表示的动作是谁做的，即不定式的逻辑主语，通常可以通过for sb. to do sth. 结构表达：
1.It is quite important for us to read good books during a general review．
2.It is not difficult fot those talented students to pass the exam.
1.It is very kind of you to tell me the truth．
2.It is stupid of him to do such a silly thing．
只能跟动词不定式的动词，常见的有: afford, agree, aim, appear, ask, believe, care，claim，decide demand, desire, determine, expect, fail, happen, hesitate, hope, intend, learn, long, manage, offer, pretend, promise, prepare, refuse, seek, swear, undertake，want, wish等。
1.He managed to solve the complicated problem.
2.The stranger offered to show me the way.
3.Mr. Smith undertook to build a new plant in South Africa.
这类动词常见的有advise, decide, find out, forget, inquire, know, learn, see, regard, remember, teach, tell, understand, wonder等。常见的疑问代(副)词有: what, when, where, which, how, whether等。
1.He does not know when to start.
2.You can decide whether to continue or to stop.
3.I will show you how to deal with it.
有时，不定式可由it代替，而把不定式放到后面去。这可以用这一结构表达：动词(如find, think，consider，feel等)+it+ 形容词+不定式。
1.She considers it necessary to make friends with him.
2.We find it difficult to finish all the homework before 9 o’clock.
1.To see is to believe.
2.To work means to earn a living．
另一种情况为主语是以aim，duty，hope, idea，job, plan，problem, purpose，thing，wish等名词为中心的短语，或以what引导的名词性从句，不定式表语对主语起补充说明作用：；例如：
1.His aim is to study abroad in the near future．
2.The most important thing is to negotiate with them about the price．
3.What I want to say is to forget all the unhappy experience．
1.There was really nothing to fear．
2.He gave me an interesting book to read．
1.Mary needs a friend to play with．
2.That girl has nothing to worry about．
3.They have a strict teacher to listen to．
4.Although the film had been on for ten minutes, I still was not able to find a chair to sit on．
1.Have you got a key to unlock the door?
2.The action to be taken is correct．
3.There is nothing to be gained by pretending．
第三种，被修饰的名词词组是不定式的同位结构。这类名词通常是表示企图、努力、倾向、目的、愿望、is算、能力、意向等意义的名词：ability, attempt, effort, impulse, inclination,wish等。例如：
1.Her daughter will make an even bigger effort to please her．
2.I have no wishto quarrel withyou．
3.Neither of them had any inclination to do business with Mary.
1.They are quite surprised to see the great changes taking place in the area．
2.They are quite surprised because they see the great changes taking place in the area．
3.He was lucky to arrive before dark．
4.He was lucky because he arrived before dark．
1.She raised her voice to be heared better．
2.She raised her voice so that she could heard better．
3.We went via Heidelberg to miss the traffic jam．
4.We went via Heidelberg so that we could miss the traffic jam．
1.The French football team played so successfully as to defeat the Brazilians．
2.The French football team played so successfully that they even defeated the Brazilians．
3.He got to the station only to be told the train had gone．
4.He got to the station and was told that the train had gone．
1)在can／could, /may／might，will／would，shall／should，must, need，dare等情态动词之后，动词不定式不带to。
1.I often heard him say that he would study hard．
2.I must have him see his own mistakes．
1.He was often heard to say that he would study hard．
2.After he had finished speaking，he was made to answer innumerable questions．
1.Help the old lady (to) carry the heavy box.
4)在had better，would rather，may／might as well，rather than，can not but等搭配之后，动词不定式也不带to。例如：
1.Unless you feel to ill to go out，I would rather not stay at home tonight．
2.She could not but criticize his foolish behaviour.
5)在make do，make believe，let drop，1et fall，1et fly，let slip，let drive，let go off，hear say，hear tell，leave go of等固定搭配中，用不带to的动词不定式。例如：
1.They let go of the rope．他们松开了绳子。
2.John let fly a torrent of abuse at me．约翰朝我痛骂了一顿。
3.I've heard tell of him．我听说过他。
4.Some of the faculty were let go for lack of the students．由于生源不足,一些教职员工被解雇了。
1.He will do anything except work on the farm．
2.There was nothing left for the enemy to do but surrender．
3.The spy was both hungry and cold；there was nothing left for him but to give in．
4.I had no choice but to wait till it stopped raining．
can not help but，can not choose but，can not but，do nothing but，have nothing to do but。例如：
I can not but admire his courage.
I did nothing but watch TV last night．
I have no choice but to give up my idea.
Why stand up if you can sit down?
Why not ask your teacher when you don't understand the meaning?
You needn't decide yet whether to study arts or science．
完成式：to+ have done
进行式：to+ be doing
1.She feels relaxed to have finished writing her thesis before the deadline．
2.The Vikings are believed to have discovered America．
3.When you called me last night, I happened to be working on the computer．
1.For twelve years, Spanish censorship did not allow Lorca's name to be mentioned and his work to be published．
2.The snow was supposed to have been blown off the mountain．
1.I decided not to ask him again．
2.Please remember not to leave the lights on when you are out．