动词不定式:“不定式符号to+动词原形”一、用作主语( ) 1. Is ______ easy to finish the design before National Day?A. thisB. thatC. itD. he( ) 2. It ______ forty-five minutes ______ there by bus.A. cost; to getB. takes; gettingC. takes; to getD. takes; to get to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.(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。
①It＋be＋名词＋to doIt's our duty to take good care of the old.②It takes sb+some time+to doHow long did it take you to finish the work?③It＋be＋形容词＋for sb＋to doIt is difficult for us to finish writing the compositionin a quarter of an hour.④It＋be＋形容词＋of sb＋to doIt is stupid of you to write down everything the teachersays.注意：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，不说明人的特性。
前面如果是名词用for。
二、用作表语( )The first thing is the teacher.A.greetB.greetingC.to greetD.to greeting( ) This house is in .A.livingB.to liveC.liveD.to living动词不定式作表语，常说明主语的内容、性质、特征。
如：The best way to improve your English is to join an English club.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)，宁可计划知道(prefer, plan, 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.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，如：...feel / find / make / ... it+adj. / n.+to do...。
如：( )I find it difficult everything.A.to rememberB.rememberC.rememberingWe think it quite important for us to learn a foreignlanguage well.He feels it his duty to help the poor.四、用作定语( ) 1.I’m hungry. Get me something ____.A eatB to eatC eatingD for eating( ) 2. –Have you got everything ready for the trip?--Yes. There’s nothing ______.A. to worry aboutB. need to worry aboutC. to worry at allD. worrying about( ) 3. He is a nice person ______.A. to work withB. working withC. worked withD. to be worked1.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时，用动词不定式的主动式。
如：1)I cant think of any good advice to give her. 动宾关系2)Basketball has also become a more popular sport for people to watch.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)Is that a good place to hang out？3)You want to know the best way to get around the city.五、用作补语( ) Their teacher often ______ them a funny story ______ his class lovely and interesting.A. tells; to makeB. talks; to makeC. says; makesD. speaks; makes动词不定式作补语时，在主动语态句里补宾语，在被动语态句里补主语，句子的宾语或主语是不定式动作的逻辑执行者。
如果不定式是to be done，句子的宾语或主语就是逻辑承受者。
1.在主、被动语态句里用带to的动词不定式作补语的动词主要有：要求允许提议(ask, allow, permit, advise)，期望邀请鼓励(expect, suppose, 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)Teenagers should be allowed to choose their own clothes.3)Email English is supposed to be used on mobile phones.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。
1)This picture makes me feel tense！2)Of course we want to see Liu Yu achieve his dreams3.be said, be sure, happen, seem等后面可以接带to的动词不定式作主语的补语。
如：1)He doesn’t seem to have many friends.2)Be sure not to miss them if they come to a city near you.( ) 1. We saw him ______ the building and go upstairs.A. to enterB. enterC. enteringD. entered( ) 2. “Don’t always make Michacl ______ this or that. He is already a big boy, dear.” Mr Bush said to his wife.A. doB. to doC. doesD. did( )3. The young lady watched her daughter ______ a yo-yo yesterday afternoon.A. to play withB. playing withC. to playD. plays( )4. Though he had often made his little sister ____, today he was made ___ by his little sister ____.A cry; to cryB crying; cryingC cry; cryD to cry; cry六、用作状语( ) 1. The ice is thick enough ______.A. to walk onB. for walkingC. to walkD. to walk on it( ) 2. The chair looks rather hard, but in fact it is very comfortable to ______.A. sitB. sit onC. be satD. be sat on⒈作目的状语★I stayed there to see what would happen.2) Bob took down my telephone number in order not to forget it.3)I stayed there so that (in order that)I could see whatwould happen.4).I hurried to Professor Wang's house only to find he was out.我匆忙的感到王教授的家可是却发现他外出了。
2.原因状语，多见于“sb.+be+adj.+to do...”结构句中。
如：1) We are glad to hear the news.2)I was surprised to see that a three-year-old baby could write so well3.结果状语，多见于“too...to”，“enough to...”"so...that..."结构句中。