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高中英语知识点之不定式
时间：　　作者：　　来源：新东方
　　定义：动词不定式是非谓语动词的一种，它没有人称和数的变化，在句子中不能独立作谓语，但它仍保持动词的特点，既可以有自己的宾语和状语。 E.g. He want his students to read the book aloud.
　　1.不定式的构成 （以动词do为例）
　　主动形式 被动形式
　　一般式 to do to be done
　　完成式 to have done to have been done
　　进行式 to be doing 无
　　完成进行式 to have been doing 无
　　2.不定式的意义
　　不定式的一般式(to do )
　　一般式表示的动作或状态，发生在谓语动词表示的动作或状态的同时或之后
　　My wish is to become a doctor
　　He seemed to be tired.
　　She stopped to have a rest.
　　不定式的被动式 (to be done)
　　当不定式的逻辑主语是这个不定式所表示的动作的承受者时,不定式一般要用被动式.
　　The building to be finished next month is for our teachers.
　　I am going to Beijing, I have something to take to my parents, do you have something to be taken to your parents?
　　如果谓语表示的动作(情况)发生时, 不定式表示动作正在进行,这时候不定式就要用进行式.（to be doing）
　　They are said to be building another bridge across the street.
　　They seemed to be talking about something important.
　　When I went to his home, he happened to be traveling around the world.
　　I'm glad to be working with you.
　　如果不定式所表示的动作或状态发生在谓语动词所表示动作或状态之前，就用完成式 (to have done) ；若是在此基础上的被动含义，就用完成被动式( to have been done).
　　He is said to have written a novel about the Long March.
　　He thought it a pity not to have invited us.
　　The assistant seemed to have been fired.
　　He is said to have been taught French when he was a child.
　　Einstein is said to have built up his theory when he was in his twenties.
　　如果不定式的动作是在谓语所表示的时间之前一直在进行的动作，就要用完成进行式.
　　They are said to have been collecting folk song in Xinjiang.
　　We're happy to have been working with the experts all the month.
　　B. 用法：
　　动词不定式具有名词、形容词和副词的特征。因此在句中可以做主语、表语、宾语、宾语补足语、定语和状语。
　　一、不定式做主语：
　　1、不定式做主语一般表示具体的某次动作。===动名词doing 表示习惯的，经常的动作。
　　e.g:& To finish the building in a month is difficult.
　　To do such things is foolish.
　　To see is to believe. (对等)
　　注: 1).& 不定式作主语时,谓语用单数
　　2). 当主语较长，谓语较短时，常用it做形式主语，而将不定式放到谓语的后面。
　　it做形式主语，不定式放在谓语动词之后常用于下列结构中：
　　(1)It is/was +adj.+of sb. to do…
　　(2) It is +adj.+for sb.+to do…
　　It is easy / difficult / hard / foolish / unwise / right / wrong / unnecessary
　　(3) it is +a +名词+ to do...
　　It is a pity / a pleasure / a pleasant thing / one's duty / an honor / a shame / a crime / no easy job… to do
　　It takes (sb.) some time / courage / patience …to do…
　　It requires courage / patience / hard work… to do…
　　*注意:& probable 和 possible 均可作表语，但possible可以用不定式作真实主语， 而probable不能用不定式作真实主语。
　　It is probable for him to come to the meeting.(错）
　　It is possible for him to come to the meeting.
　　It is possible / probable that he will come to the meeting.
　　二、不定式做表语
　　主语是以aim& duty& hope& idea intention& plan&& job&& suggestion&& wish& purpose& task 等为中心词的名词词组 或以 what 引导的名词性从句表示，后面的不定式说明其内容, 不定式作表语常表示将来或现在的动作或状态。
　　eg :My idea is to climb the mountain from the north.
　　Your mistake was not to write that letter.
　　What I would suggest is to start work at once.
　　三& 动词不定式作宾语
　　以不定式结构为宾语的动词有：
　　ask, agree, care, choose, demand, decide, expect, fail, help, hope, learn, manage, offer, plan, prepare, pretend, promise, refuse, want, wish等只能用动词不定式作宾语。
　　口诀（接不定式作宾语的动词）
　　想要学习 早打算（ want learn plan）
　　快准备& 有希望（ prepare hope wish expect）
　　同意否& 供选择（agree offer choose）
　　决定了& 已答应（decide be determined promise）
　　尽力去&& 着手做（manage undertake）
　　别拒绝&& 别假装（refuse pretend）
　　失败不是属于你（fail）
　　e.g.Tom refused to lend me his pen.
　　We hope to get there before dark.
　　The girl decided to do it herself.
　　*注意:某些及物动词可用-ing也可用动词不定式作宾语但意义不同的有
　　stop / go on / remember / forget / regret / try / mean / can't help /&be&used&to
　　四． 动词不定式做定语
　　1.不定式作定语需要后置
　　2. 作定语的不定式与被修饰的名词或代词存在着两种主要的逻辑关系，即被修饰的名词和代词是不定式的逻辑主语 （逻辑上的主谓关系）或逻辑宾语（逻辑上的动宾关系）。
　　1）不定式前的名词是它的逻辑主语。
　　He is the doctor to do the operation.
　　2) 不定式和它所修饰的名词是逻辑上的动宾关系。
　　I have a lot of things to do.
　　3）不定式前的名词是它修饰的对象。
　　This is the right time to start.
　　注意：如果不定式所修饰的词是way 或 place, 介词可省略。
　　He has no way to go (by).&&This is the best place to work (at)
　　五．宾语补足语
　　He want you to be his assistant.&& I saw her cross the street.
　　[注1] 如果谓语动词为感官动词或使役动词，则作宾补的不定式不可带to，这些动词有see, hear, feel, watch, have, make, let等。
　　I felt my blood run cold.&&& What made you think like that?
　　但如果句子是被动语态，则to不可省略。
　　He was made to clean the windows as a punishment.
　　Someone was heard to come up the stairs.
　　[注2] 1.谓语动词help后可接带to或不带to的不定式作宾补。用不带to的不定式表示帮助者直接参与动作；用带to的不定式表示主语没有直接参与动作。
　　They helped me carry the boxes.
　　This kind of soap will help you to wash the clothes more easily.
　　2.在美式英语或非正式文体中，help后用作宾补的不定式均不带to。
　　3.help后可以直接用带to或不带to的不定式作宾语。
　　They helped (to) carry the furniture upstairs.
　　[注3]look at及listen to后用作宾补的不定式不带to（这主要是美式英语）。
　　We have been listening to the radio tell a long story.
　　六．表语补足语， 当不定式与主语存在逻辑上动宾关系的时候，用主动表被动。
　　That is hard to say.&& The chair is comfortable to sit in.
　　七．不定式做状语
　　不定式做状语修饰动词、形容词、副词等，表示目的、原因、结果、条件等。
　　1、表目的
　　e.g. To learn a foreign language well, you must try your best&&& (主语一致)
　　He came here to attend an important meeting.
　　He came here in order to see Charlie.
　　I turned the radio down so as not to disturb him
　　注：表示目的的不定式可以置于句首，这也是区别于 其他功能的标志之一。
　　* 但是，置于句首表示目的的不定式可以是to, in order to ，但却不可以是so as to.
　　eg: To draw maps properly, you need a special pen.
　　In order to draw maps properly, you need a special pen.
　　To get the best results, use clean water.
　　To be elected monitor of our class, he gave money to us.
　　* 放在句末时，to do 表示目的，不可有“，”若有用doing 表示伴随的目的
　　e.g. He bowed to us to thank us for helping him find the way.
　　He worked day and night, hoping to finish the work beforehand.
　　注：1. 不定式结构表示目的时，通常句子的主语就是它的逻辑主语(主语一致)
　　e.g.He bought a bicycle to go to town more quickly.
　　He went home to see his mother.
　　例外 eg: He opened the door for the children to come in.
　　They sent a man to mend the window.
　　2、表结果
　　不定式结构表示结果更常见于下列句型
　　① so …as to …
　　Would you be so kind as to lend me your bicycle / tell me the time?
　　② such (…) as to …
　　I'm not such a fool as to believe that.
　　③ adj./adv. + enough to …
　　The boy is old enough to go to school.
　　④ too … to …
　　His eyesight is too poor to read such small letters.
　　⑤only to find , only to be told 出乎意料之外的结果
　　3． 原因不定式可以用于动词、形容词或-ed分词后表示原因。
　　He was too excited to get high marks.
　　八．同位语
　　Is this your purpose, to avoid being punished?
　　九．独立成分
　　To tell you the truth, I don't like you. They arrived here at 11:55 a.m., to be exact.
　　类似的有：to be frank坦率地说，to hear him talk听他说话的口气，to cut a long story short 长话短说，等等。
　　C．不定式的各种结构
　　1．宾格词 + 不定式
　　1）普通结构& 此结构中的宾格词为名词或代词的宾格，宾格词是谓语动词的宾语，同时又是不定式的逻辑主语，不定式和宾格词一起构成复合宾语。
　　I want Henry to come. She expects this to be true. I heard them sing yesterday.
　　2) “there to be + 宾格词”结构
　　此结构的宾格词仍是不定式的逻辑主语，只是它位于不定式to be 的后面。
　　I don't want there to be any misunderstanding.
　　3) 各种形式的不定式都可以用于此种结构中。
　　The judge wanted the man to be punished.
　　He expected each of his students to be working hard for the coming exam.
　　2．主格词 + 不定式
　　当上一种结构变为被动语态时，就出现了此种结构，此结构中，不定式都要带to，主格词是不定式的逻辑主语，不定式在句中作主语补足语。
　　They are allowed to go. ← We allowed them to go.
　　He was seen to enter the store. ← I saw him enter the store.
　　3．for + 宾格词 + 不定式
　　此结构中，宾格词是不定式的逻辑主语，这种结构在句中可作：
　　1）主语& It is difficult for us to learn a second foreign language.
　　2）宾语& I consider it necessary for her to learn French.
　　3）表语& The best thing is for us to make our own decision.
　　4）定语& There is a lot of work for us to do.
　　5）状语& He opened the door for the car to enter.
　　The book is too easy for them to read.
　　4．with/without + 宾格词 + 不定式
　　此结构在句中常作原因状语，宾格词是不定式的逻辑宾语。
　　With so much work to do, I shall not be able to watch the match with you.
　　Without anything to eat, he died of hunger.
　　5．疑问词 + 不定式&& 此结构相当于名词词组，在句中可作：
　　1） 主语 When to visit that farm has not been decided yet.
　　2） 宾语 We must know how to operate this machine.
　　3） 表语 The problem now is how to collect enough money.
　　4） 同位语 The problem what to do next is unknown.
　　注意& intend, plan, hope, expect, mean, promise, want, think, wish, were (was), would like, should like + 不定式完成式，可表过去没有实现的愿望，期待和计划。
　　He intended to have come. = He intended to come, but he didn't.
　　She wished to have bought a car. = She wished to buy a car, but she didn't.
　　I meant to have called on you, but I was too busy.
　　She hoped to have passed the exam. (but she didn't)
　　I would like to have gone abroad. (but I didn't) D
　　D．不定式的否定式
　　通常是在不定式前加not，表示较强的否定意义时可用never。
　　I told him not to touch the equipment.&& You must promise never to do that again.
　　E．特殊动词不定式的“省略与保留”
　　一、不定式符号的省略与保留
　　1. 在had better, would rather, would rather...than, would sooner...than, cannot but, why (not)等结构后面的不定式符号to通常被省略。如:
　　You'd better tell her the truth. 你最好告诉她真相。
　　2. 动词不定式短语作介词but, except, besides的宾语,且介词之前有行为动词do或它的其它形式时,不定式符号to通常被省略。如:
　　What do you like to do besides swim?
　　除了游泳,你还喜欢干什么?
　　My mother could do nothing but wait for the doctor to arrive.
　　妈妈只好等着医生的到来。
　　Now he had given himself no choice but to tell her. (本句中不定式符号to不可省略)
　　当时他毫无选择的余地,只好告诉她了。
　　3.两个或多个不定式短语表示并列关系时,后面不定式短语的不定式符号to通常被省略;如果表示对比关系,则不定式中的不定式符号to通常要保留。如:
　　They didn't tell me whether to go on or to stop.(对比关系)
　　他们没有告诉我是继续下去还是停止。
　　She told the child to stay there and wait till she came back.(并列关系)
　　她让孩子待在那里等她回来。
　　4.在某些感官动词或使役动词(如 hear, listen to, notice, observe, see, watch,
　　make等)之后充当宾语补足语的不定式中,不定式符号to总是被省略,但在被动语态的句子中,不定式符号to通常要保留。如:
　　They made that man work all the morning.
　　他们让那个人干了一个早晨。
　　That man was made to work all the morning.
　　那个人被要求干了一个早晨。
　　5. 不定式短语作表语,不定式符号to常常要保留,但当what引导的名词性从句作主语,或all, everything等后接定语从句作主语,从句谓语部分含有动词do或do的其他形式时,作表语的不定式可以保留也可省略不定式符号to。如:
　　The greatest happiness is to work for the happiness of all.
　　最大的幸福就是为大家的幸福而工作。
　　The only thing I can do now is (to)go on by myself.
　　我现在唯一能做的就是靠自己继续进行下去。
　　二、不定式符号后面动词的省略与保留
　　1. 为了避免重复,在hope, wish, want, like, love, decide, plan, mean, prefer,
　　want, have to, be able to, be going to, used to, ought to等动词及习语后面出现与上文相同的不定式时,常保留不定式符号to,而把其它部分省略。如:
　　Ms King lied to us because she had to.
　　金女士跟我们撒了谎,因为她不得不这样做。
　　－I heard that you would go to Dalian for your holiday.
　　我听说你要去大连度假。
　　－I planned to, but I have some important business to deal with.
　　我原计划去的,但有重要的事情要处理。
　　2.当不定式在ask, advise, persuade, wish, allow, permit, tell, expect, force,
　　invite, beg等动词后面充当宾语补足语时,为了避免重复,常保留不定式符号,而把后面的动词省略。如:
　　She wants to come but her parents won't allow her to.
　　她想来,但她的父母不允许。
　　If he doesn't want to go there, don't force him to.
　　如果他不想去那里,别强迫他。
　　He didn't come, though we had invited him to.
　　虽然我们邀请了他,但他没来。
　　－Did your husband give up smoking?
　　你丈夫戒烟了吗?
　　－No. He was advised to, but he wouldn't listen.
　　没有。有人劝过他,但他就是不听。
　　3. 在特定的上下文中,为了避免重复,如果不定式为一般式to be...或完成式to have done时,则不定式符号to和be或have常一并保留,be或have之后的部分通常要省略。如:
　　－Aren't you the headmaster?
　　你难道不是校长吗?
　　－No, and I don't want to be.
　　我不是,而且我也不想当。
　　－Hasn't he finished writing the report?
　　难道他还没写完报告吗?
　　－No, but he ought to have.
　　是的,但他本来应该写完。
　　F. 常见的含有动词不定式的句式主要有以下几种：
　　一.It takes sb. some time （money）to do sth.
　　某人花费多少时间（金钱）做某事。例如：
　　1. It often takes me half an hour to watch TV every evening.
　　每天晚上我常常用半小时看电视。
　　2. It took me ten yuan to buy the book last week.
　　上周我花了10元买那本书。
　　3. How long will it take them to finish the work?
　　完成那项工作需要花费他们多少时间？
　　在使用该句式要注意的是：sb. 如果代词表示用宾格；take随时态改变；句中的时间用段时间，对此提问用how long。
　　例：It takes us more than two hours to do our homework every day.
　　It took us more than two hours to do our homework yesterday.
　　It will take us more than two hours to do our homework tomorrow.
　　How long did it take you to do your homework yesterday?
　　二. It's time to do sth. 该做某事了，同义句为：
　　It's time for sth. / doing sth. 例：
　　It's time to go to school. 该上学了。
　　（It's time for school.）
　　It's time to get up. 该起床了。
　　（It's time for getting up.）
　　此句可以扩展为：It's time for sb. to do sth.
　　是某人做某事的时间了。
　　for sb. to do sth. 是动词不定式的复合结构。例：
　　It's time for me to work.
　　到我工作的时间了。
　　It's time for you to go to school.
　　到你们上学的时间了。
　　三. 主语＋be（not）+adj.+enough to do sth.
　　（某人、某物）足够（不能）做某事。例：
　　The boy is old enough to go to school.
　　这个孩子到了上学年龄。
　　I'm tall enough to reach the top of the tree.
　　我够高能够到树顶。
　　*1. 此句是肯定句时，可以用主＋be＋so＋adj.＋that的句型（即so…,that…表示的结果状语从句）来替换。
　　The boy is so old that he can go to school.
　　I'm so tall that I can reach the top of the tree.
　　2. 此句是否定句式时，既可以用so…that…引导的结果状语从句来替换，还可以用too…to…句式替换。例：
　　He is not old enough to go to work.
　　他太小不能去上班。
　　He is so young that he can't go to work.
　　He is too young to go to work. 再如：
　　The box is not light enough for me to carry.
　　这个箱子太重我搬不动。
　　The box is too heavy for me to carry.
　　The box is so heavy that I can't carry it.
　　四. sb. +be ready + to do sth. （某人乐意做某事）
　　He is always ready to help others.
　　（他总是乐于帮助别人）
　　I'm always ready to make new friends.
　　我总是乐于结交新朋友。
　　五. It's +adj. + for / of sb. to do sth.
　　对某人来说做某事…例：
　　It's dangerous for children to play football in the street.
　　对孩子来说在街上踢足球是很危险的。
　　It's good for us to take more exercise.
　　对我们来说多运动是有益的。
　　It's very kind of you to say so.
　　你这样说真是太好了。
　　It's very kind of you to help me.
　　你真好，肯帮我。
　　该句式中，引导动词不定式的逻辑主语的介词用for还是of，主要取决于前面的形容词。如果形容词是描述动词不定式的行为者的性格、品质的。如：kind, good, nice, wrong, right, clever, careless, foolish等，应用of；如果形容词仅仅是描述事物，不是对动词不定式的行为者的品质进行评价的，就用for. 常见这类形容词有difficult, easy, hard, important, dangerous等。
　　It's wrong of you to do it.
　　你做这件事是错的。
　　It's hard for you to be a lawyer.
　　对你来说做律师很困难。
　　六. 主+would like / love to do sth. …喜欢（想做某事）
　　I'd like to go there with you.
　　我很想和你一起去那。
　　I'd love I like to help you study English.
　　我很愿意帮你学英语。
　　此句式还可以扩展为：
　　would like / love sb. to do sth.
　　“喜欢/想让某人做某事。”
　　I'd like you to stay here.
　　我想让你留在这。
　　I'd like them to help me.
　　我想让他们帮助我。
　　七. had better do sth. （…最好做…）
　　It's very cold outside, you'd better put on your coat.
　　外面很冷，你最好穿上大衣。
　　We'd better go right now.
　　我们最好马上去。
　　…had better do 的否定式为…had better not do. （在better后加not即可）例：
　　You'd better not speak when your mouth is full of food.
　　满嘴食物时你最好别讲话。
　　八. Why don't you +动词原形+…？（Why not＋动词原形…？）你为什么不…？
　　这本书有点难，为什么不读些容易的？
　　This book is a bit hard, why not read something easier?
　　It's warm here, why don't you take off your coat?
　　这很暖和，你为什么不脱掉外衣？
　　There is a seat, why not sit down?
　　还有座位，怎么不坐下？
　　九. Would / Will / Could you please ＋动词原形＋…？
　　请你…好吗？（用来请求对方为自己做某件事）
　　Would you please bring some water with you?
　　请你带点水来好吗？
　　Will you please help her with her maths?
　　请你帮她学数学好吗？
　　十. …prefer …to do sth. rather than do sth. …宁愿…也不愿…
　　I prefer to stay at home rather than go out.
　　我宁愿呆在家里，也不愿出去。
　　She prefers to be poor rather than get money in such a way.
　　她宁愿受穷也不愿以这种方式挣钱。
　　十一. It's one's turn to do sth.
　　该轮到谁做某事了。
　　one's用形容词性物主代词或名词所有格来替换。例：
　　It's my turn to be on duty.
　　该轮到我值日了。
　　It's Li Ping's turn to clean the blackboard.
　　该轮到李平擦黑板了。
　　It's our turn to do the cleaning.
　　该轮到我们做扫除了。
　　It's Danny's turn to give a talk.
　　该轮到Danny做报告了。
　　十二. 主语＋be＋形容词＋to do sth. …做某事如何。例：
　　I'm sorry to hear that.
　　听到这事很难过。
　　I'm glad to see you again.
　　再次见到你我很高兴
　　(实习编辑：彭莉君)
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