英语动词不定式的结构及用法

编辑: 逍遥路 关键词: 高中英语 来源: 高中学习网


  不定式的语法功能:除不能作谓语,其他句子成分都可。常见考法有:1.不定式作状语;2.it作形式主语代替后面的不定式;3.不定式的否定形式4.被动语态中的不定式;5.不定式省to情况;6.不定式作定语的情况。

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1不定式做句法成分

  不定式短语作主语时,可以直接放在句首,但在很多情况下,尤其是在疑问句和感叹句中,往往放在谓语之后,而用先行代词it作形式主语。不定式由“ to十动词原形”构成,其否定形式是“ not to do”。不定式可以带宾语或状语构成不定式短语,没有人称和数的变化,但有时态和语态的变化.不定式可作主语、宾语、状语、表语和定语,但不能单独作谓语.不定式的逻辑主语有时用“ for十名词或代词宾格”构成。

  1.不定式作主语

  To see is to believe.

  常用it作形式主语

  It's for sb/It's of sb

  1)for sb. 常用于表示事物的特征特点,表示客观形式的形容词,如easy, hard, difficult, interesting, impossible等:

  It's very hard for him to study two languages.

  2)of sb的句型一般用表示人物的性格,品德,表示主观感情或态度的形容词,如good, kind, nice, clever, foolish, cruel, right。

  It's very nice of you to help me

  To serve the people is my great happiness. 为人民服务是我的最大幸福。

  It is right to give up smoking.戒烟是对的。

  不定式作主语常见句型如下:

  a.It is + adj (easy, important, difficult…) + 不定式

  b. It is + n (a pity, a pleasure, one’s duty, a shame) + 不定式

  c. It takes/needs/requires + some time (hours, months, days, patience…) + 不定式

  It’s important for us to learn English well. 我们学好英语很重要。

  It’s my duty to teach you how to be a useful person. 教你如何做一个有用的人是我的职责。

  It requires patience to be a good teacher. 当个好老师需要耐心。

  2.不定式作宾语

  不定式短语作宾语时,位于及物动词之后。可以直接用不定式作宾语的动词很多,常见 的有:agree, afford, tend, ask, decide, determine, expect, fail, hope, learn, intend, manage, offer, plan, promise, refuse, want, wish等。例如:

  I offered to help her, but she refused. 我提出帮助她,但她拒绝了。

  He pretended not to hear me. 他假装没听见我(的声音)。

  I don’t want to sound like I’m speaking ill of anybody, but the manager’s plan is unfair.

  我不想听起来象在说别人坏话,但经理的计划是不公平的。

  如果还带有宾语补足语。往往把不定式宾语放在宾语补足语之后,而用 it作形式宾语。常用动词有feel, think, find, believe,? consider, make等。例如:

  I find it interesting to work with him. 我发现与他共事很有趣。

  We feel it our duty to help others. 我们认为帮助别人是我们的责任。

  Science and technology has made it possible for man to fly in space.科学技术已经使人类能够遨游太空了。

  下列动词后可接疑问词+不定式:

  teach、decide、wonder、show、learn、forget、ask、find out、advise、know等

  例如:

  Can you teach me how to use the computer? 你能教我使用电脑吗?

  I don’t know what to do next. 我不知道下一步怎么办。

  I want to speak to Tom.

  Please show us how to do that.

  3.不定式作宾补

  不定式作宾语补足语位于宾语之后,表示宾语的动作或状态。常用于以下动词之后:ask, tell, advise, allow, enable, expect, force, get, like, order, teach, want, invite, wish, beg等。例如:

  He asked me to do the work with him.他要我与他一起干。

  You should get more people to help you.你应该多找些人帮你。

  The teacher expected everyone to study hard,老师希望每个人都努力学习。

  注意:

  a. 在see,watch,look at,notice, observe,have,let,make, hear,listen to,feel,help等词后的补足语中,不定式不带 to。例如:

  I often hear him sing the song.我经常听见他唱这只歌。

  The teacher usually made the students recite the text.老师通常让学生背颂课文。

  Would you please help me (to) repair my bike?请帮我修理自行车好吗?

  但是这些句子如果变成被动结构时, 就必须带 to。例如:

  He is often heard to sing the song.人们常听到他唱这只歌。

  The students were usually made to recite the text.学生们常被要求背颂课文。

  b. 不定式动词在介词 but,except,besides后面时,如果这些介词之前有行为动词 do的各种形式,那么,这些介词后的不定式不带 to,否则要带 to.如:

  She could do nothing but cry.她只是哭。

  What do you like to do besides swim? 除了游泳你还喜欢干什么?

  c.主句含有不定式,后面有rather than, rather than后省to。

  d. Why not、had better、would rather、can’t but等词后省to。如:

  He could not but walk home.他只好走回家。

  注意:e. 常用带不定式作宾补的几种情况:

  (a) 主语 + ask / require / tell / order / force / get / want / like + sb.to do sth.

  (b)主语 + think / judge / suppose / believe / consider / imagine / consider / feel + sb. + to be/ to have done

  (c)主语 + call on / upon / depend on / wait for / ask for + sb.+ to do sth.

  a. Father will not allow us to play on the street.

  b. We believe him to be guilty.

  4.不定式作表语

  不定式可放在连系动词或be动词后面,形成表语。

  例如:

  My job is to help the patient.我的工作是帮助病人。

  Our most important task now is to make a plan.我们现在最重要的任务是制定一个计划。

  注:作表语的不定式都带to,但当主语部分有实义动词do时,to可以省略。

  例如:

  The only thing we can do now is wait and see.我们现在唯一能做的事就是等着看。

  My work is to clean the room every day.

  5.不定式作定语

  不定式做定语通常要放在被修饰的词后。例如:

  I have some books for you to read.我有一些书给你看。

  We have a lot of homework to do today.今天我们有很多作业要做。

  He hasn’t kept his promise to write to his parents regularly.他没有信守定期给父母写信的诺言。

  注意:a.作定语的不定式如果是不及物动词,或者不定式所修饰的名词或代词是不定式动作 的地点、工具等,不定式后面须有相应的介词。例如:

  He is looking for a room to live in.他在找房子住。

  There is nothing to worry about.没有什么可担心的。

  Please give me a knife to cut with.请给我一把刀用。

  但是,不定式所修饰的名词是 time,place或 way,不定式后面的介词习惯上要省去。例如:

  He had no money and no place to live.他没有钱,也没有房子住。

  b.当作定语的不定式所修饰的名词或代词是不定式动作的承受者时,不定式既可以用主动语态,也可用被动语态,但其含义有所不同.试比较:

  Have you anything to send? 你有什么东西要寄吗?(不走式 to send的动作执行者是 you)

  Have you anything to be sent? 你有什么要(我或别人)寄的东西吗?(不定式 to be sent的动作执行者是已被省略的 me或 someone else)

  c.下列词语后常接不定式作定语:chance、wish、right、courage、need、promise、time、opportunity、way、the first、the second、the last、the only等。

  He is always the first to come and the last to leave.他总是第一个到,最后一个走。

  I have a lot of work to do.

  6.不定式作状语

  作状语,表示目的、原因、结果或条件

  例如:

  I came here to see you.(目的)我来是看你的。

  We were very excited to hear the news.(原因)听到那消息我们很激动。

  He hurried to the school to find nobody there.(结果)他匆忙赶到学校,结果发现没有人。

  To look at him, you would like him.(条件)如果你见到,你会喜欢他的。

  in order (not) to, so as (not) to用来引导目的状语,

  在enough to, too … to, so… as to, such….as to, only to …结构中不定式作结果状语,其中only to…用于表示意想不到的结果。例如:

  The girl was so kind as to help the old man off the bus.那个女孩很热心,帮助老人下车。

  In order to pass the exam, he worked very hard.为了通过考试,他刻苦努力学习。

  We ran all the way so as not to be late.我们一路跑着,以免迟到。

  He is too old to do that.他太老了,不能做那件事了。

  The room is big enough to hold us.房间足够大,可以容纳我们。

  He hurried to the station only to be told the train had gone.他匆忙赶到车站,结果被告知火车已经开走了。

  不定式也可在作表语用的形容词后面作状语。例如:

  I am very glad to hear it.我非常高兴听到这事。

  The question is difficult to answer.这个问题很难回答。

  1)目的状语

  to… ,only to (仅仅为了),in order to, so as to, so(such)… as to… (如此……以便……)

  He ran so fast as to catch the first bus.

  I come here only to say good-bye to you.

  2)结果状语

  What have I said to make you angry.

  He searched the room only to find nothing.

  3)原因状语

  I'm glad to see you.

  用作介词的to

  to 有两种用法: 一为不定式+动词原形; 一为介词+名词/动名词, to 在下面的用法中是第二种,即to+ 名词/动名词:

  admit to承认,confess to承认,be accustomed to 习惯于,be used to 习惯于,

  stick to 坚持,turn to开始,着手于,devote oneself to 献身于,

  be devoted to 致力于, look forward to 盼望,pay attention to 注意

  7.省to 的动词不定式

  1) 情态动词 ( 除ought 外,ought to):

  2) 使役动词 let, have, make:

  3) 感官动词 see, watch, look at, notice , observe, hear, listen to, smell, feel, find 等后作宾补,省略to。

  注意:在被动语态中则to 不能省掉。

  The boss made them work the whole night.

  =They were made to work the whole night.

  4) would rather,had better:

  5) Why… / why not…:

  6) help 可带to,也可不带to, help sb (to) do sth:

  7) but和except:but前是动词do时,后面出现的动词用不带to的动词不定式。He wants to do nothing but go out.

  8) 由and, or和than连接的两个不定式,第二个to 可以省去:

  He wants to move to France and marry the girl.

  9) 通常在discover, imagine, suppose, think, understand等词后,可以省去to be:He is supposed (to be) nice.

1动词不定式的否定式

  放在不定式符号to 前面

  Tell him not to shut the window…

  She pretended not to see me when I passed by.

  不定式特殊句型too…to…

  1)too…to太…以至于不能…

  He is too excited to speak.

  2) 如在too前有否定词,则整个句子用否定词表达肯定, too 后那个词表达一种委婉含义,意为"不太"。

  It's never too late to mend.(谚语)

  3)当too 前面有only, all, but时,意思是:非常… 等于very。

  I'm only too pleased to be able to help you.

  He was but too eager to get home.

  不定式特殊句型so as to

  1) 表示目的;它的否定式是so as not to do。

  Tom kept quiet about the accident so as not to lose his job.

  2) so kind as to ---劳驾

  Would you be so kind as to tell me the time?

  不定式的形式和主、被动

  形式主、被动 主动 被动

  一般式 to do to be done

  进行式 to be doing

  完成式 to have done to have been done

  完成进行式 to have been doing

  1) 一般式:有时与谓语动词表示的动作同时发生,有时发生在谓语动词的动作之后。

  He seems to know this.

  I hope to see you again. = I hope that I'll see you again.

  2) 完成式:表示的动作发生在谓语动词表示的动作之前。

  I'm sorry to have given you so much trouble.

  3) 进行式: 表示动作正在进行,与谓语动词表示的动作同时发生。

  He seems to be eating something.

  4) 完成进行式: 表示动作或状态从谓语动作之前一直持续到谓语动作发生。

  She is known to have been thinking over the problem for many days.

1动名词与不定式

  1) 动名词与不定式的区别:

  动名词表达的是: 状态,性质,心境,抽象,经常性,已发生的

  不定式表达的是: 目的,结果,原因,具体,一次性,将发生的

  2) 接不定式或动名词,意义相近。

  begin/ start to do = begin/ start doing; continue to do =continue doing

  3) 不定式作独立成分

  例如:To tell the truth,I don’t agree with you.说实话,我不同意你的观点。

  4)不定式与疑问词 who,which,when,where,how,what等连用,在句中起名词作用,可充当主语、表语、宾语等.

  例如:

  He didn’t know what to say. (宾语)他不知道说什么。

  How to solve the problem is very important.(主语)如何解决问题是非常重要的。

  My question is when to start. (表语)我的问题是何时开始。

  注意:在与 why连用时,只用于 why或 why not开头的简短疑问句中,后面紧跟的动 词不定式不带 to.例如:

  Why not have a rest? 为什么不休息一下呢?

  5)不定式的复合结构 … for / of sb to do sth

  以it为形式主语或形式宾语引导的复合结构,如果其前的形容词是指行为的性质就用:for sb. to do sth.。这种句式中的常用形容词有:easy, difficult, hard, important, necessary, possible, impossible等。

  如果该形容词是指行为人的性质和特征,则用of sb. to do sth.。这种句式中的常用形容词有:right, wrong, brave, careful, careless, clever, wise, stupid, cruel, foolish, good, honest, kind, nice, silly等。这种复合结构在句中可作主语、表语、宾语、定语、状语等

  It is necessary for me to learn English well.我学好英语十分必要。

  It’s difficult for us to master a foreign language.我们掌握一门外语是困难的。

  It’s very kind of you to come to see me.你来看我太好了。

  It’s careless of the boy to make the same mistake again.那个孩子又犯了同样的错误,真是太粗心了。

  6)不定式在句中用主动式还是被动式, 多数情况下是容易判别的,但有时的确比较复杂, 请注意以下几点:

  a. 不定式修饰的名词或代词和不定式逻辑上构成主谓关系时,不定式往往用主动形式.

  Have you got a key to unlock the door?(A key unlocks the door.)你有钥匙开门吗?

  b. 不定式和它前面被修饰的名词或代词构成逻辑上的动宾关系,又和该句主语构成逻辑上的主谓关系时,不定式常用主动形式.

  I have got a letter to write.( I write letter.)我有一封信要写。

  He needs a room to live in.( He lives in a room.)他有一个房间住。

  I know what to do.( I do what.)我知道做什么。(我自己做)

  但这句如改为下列形式,不定式就得用被动形式:

  I know what is to be done.我知道能做什么。(表示可能性,客观)

  这是因为 what is to be done是宾语从句,从句中的主语 what是动词 do的动作对象。

1不定式的时态

  ①不定式的一般形式所表示的动作,通常与谓语的动作(状态)同时(或几乎同时)发生,或是在它之后发生, to do…,例如:

  I saw him go out.我看见他出去了。

  She wanted to be a doctor when she grew up.她长大了想当医生。

  ② 如果谓语表示的动作(情况)发生时,不定式表示的动作正在进行,这时不定式就要用进行式。 to be doing …

  例如:

  I am very glad to be working with you.我很高兴与你共事。

  Some students pretended to be reading English when the teacher came in.

  当老师进来时,一些学生假装在看书。

  ③ 如果不定式的动作发生在谓语动词之前,就要用完成式。 to have done …,例如:

  I’m sorry to have kept you waiting.对不起,让你久等了。

  He is said to have left the stage already as he has become an official.

  据说他已经离开舞台了,因为他已经当了官员了。

1不定式的语态

  当不定式逻辑上的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形 式。to be done / to have been done, 例如:

  He asked to be sent to work in the countryside.他要求被派到农村去工作。

  It is impossible for our hopes to be realized.我们的希望不可能实现。

  The book is said to have been translated into English. 据说这本书已经被翻译成英语了。

1不定式的否定形式

  不定式的否定形式由not加上不定式构成,即:

  not to do sth, not to be doing sth, not to have done sth

  例如:

  Mother told the children not to play football in the street.妈妈要孩子们不要在大街上踢足球。

  In order not to miss the train they got up early.为了不错过火车,他们很早就起床了。

  He pretended not to have seen his friend 他假装没有看见他的朋友。

1误区提醒

  1.不定式的不同形式误用;2.被动语态中仍然省to;3.否定形式not位置弄错;4.主动语态中该省to不省; 5.不定式作定语时丢内容


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