上海初中英语动词不定式精讲精练 动词不定式是动词的一种非谓语形式，没有人称和数的变化，不能单独作句子的谓语其构成形式为"to+动词原形"，to为动词不定式的符号，本身无意义动词不定式具有两大特点： 1.具有动词的特点，因此，后面可以跟表语、宾语或状语，构成动词不定式短语 2.具有名词、形容词或副词的特点，可以在句子中用作主语、宾语、宾语补足语、状语、定语、表语及同位语等1.作主语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.骑自行车到那儿将花费我们半个小时To make up for lost time is not possible.要弥补失去的时光是不可能的To lean out of the window is dangerous.身子探出窗外很危险To save money now seems impossible.现在好像不可能存钱2)用it作形式主语，把真正的主语不定式置于句后，常用于下列句式中如：①It+be+名词+to doIt's our duty to take good care of the old.这是照顾老人是我们的责任。
②It takes sb+some time+to doHow long did it take you to finish the work?你花了多少时间来完成这项工作吗？③It+be+形容词+for sb+to doIt is difficult for us to finish writing the composition in a quarter of an hour.我们难以在四分之一小时内完成这篇作文It is stupid of you to write down everything (that) the teacher says.It is an offence to drop litter in the street.在马路上乱丢废物是违章的④It seems(appears)+形容词+to doIt seemed impossible to save money.在句型③中，常用表示客观情况的形容词，如：difficult,easy,hard,important,impossible,necessary 等；在句型④中，常用careless,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise等 表示赞扬或批评的词。
在不定式前的sb，可看作其逻辑主语这一句式有时相当于Sb is+形容词+to do句式 ，如：It's kind of you to help me with my English.=You are kind to help me with my English.⑤It + 不定式结构可位于believe/consider/discover/expect/find/think和wonder之后He thought it would be safer to go by train.他认为乘火车比较安全He will find it is hard to make friends.他会感觉到交朋友困难⑥不定式的完成式也可作句子的主语To have made the same mistake twice was unforgivable.两次犯同样的错误是不可原谅的It is better to have loved and lost than never to have loved at all.爱过而后失去了爱，比从未爱过要好3)举例（1） It's easy (for me) to do that.我做这事太容易了easy, difficult, hard, important, possible, impossible, comfortable, necessary, better;the first, the next, the last, the best, too much, too little, not enoughIt's so nice to hear your voice.听到你的声音真高兴。
It's necessary for you to lock the car when you do not use it.当你不用车的时候，锁车是有必要的2） It's very kind of him to help us. 他帮助我们，他真好Kind, nice, stupid, rude, clever, foolish, thoughtful, thoughtless, brave, considerate(考虑周到的), silly, selfish(自私的)例句:It was silly of us to believe him. 我们真愚蠢，竟然相信了他It seemed selfish of him not to give them anything. 他不给他们任何东西，这显得太自私了注意：（1） 其他系动词如，look，appear等也可用于此句型（2） 不定式作为句子成分时，动词用单数形式3） 当不定式作主语的句子中又有一个不定式作表语时，不能用It is… to…的句型(对)To see is to believe. 眼见为实错)It is to believe to see.练习1. It's our 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) 3.建造这座立交桥将花费工人们一年多的时间。
It will _________ the workers over a year _________ _________ the flyover.(北京市海淀区) 4. It's very 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)3作宾语1) 以下动词后，只能跟不定式作宾语afford （付得起），agree（同意），aim(力求做到)，appear（显得），arrange（安排），ask（要求），attempt （试图），care（想要），choose（决定），claim（声称），condescend（屈尊），consent（准许），decide（决定），demand（要求），determine（决心），endeavor（竭力），expect（期待），fail（未履行），help（帮助），hesitate（犹豫），hope（希望），learn（学会），manage（设法），neglect（疏忽），offer（主动提出），plan（计划），prepare（准备），pretend（假装），proceed（接着做），promise（答应），prove（证明），refuse（拒绝），resolve（解决），seem（觉得好像），swear（发誓），tend（往往会），threaten（预示），undertake（承诺），volunteer（自愿做），vow（发誓），want（想要），wish（希望）举例：The driver failed to see the other car in time.司机没能及时看见另一辆车。
I happen to know the answer to your question.我碰巧知道你那道问题的答案2） 动词+疑问词+ 不定式decide,know,consider forget,learn,remember,show,understand,see,wonder,hear,find out,explain,tellPlease show us how to do that. 请演示给我们如何去做There are so many kinds of tape-recorders on sale that I can't make up my mind which to buy.有这么多的录音机，我都拿不定主意买哪一种注意：疑问词带不定式在句中作成分时，谓语动词用单数The question is how to put it into practice.问题是怎样把它付诸实施3)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，即：主语+动词+it+补语+to do句式如：We think it quite important for us to learn a foreign language well.He feels it his duty to help the poor.I find it difficult to learn English well.练习：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. slept D. to fall asleep (湖南省)4作补语1) 动词+宾语+不定式(to do)advise allow believe cause challenge compel declare encourage forbid force find hire induce instruct invite like order permit persuade remind request require select send suppose tell train urge例句：a. Father will not allow us to play on the street.父亲不让我们在街上玩耍。
b. We believe him to be guilty.我们相信他是有罪的练习1. Robert often asks us ______ his Chinese, so his Chinese is much better than before. A. help him B. to help him with C. to help with D. helps him with (江苏省) 2. Mr Li often teaches his Japanes。