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动词不定式
英语语法--动词不定式
动词不定式
7.1 不定式作宾语
1) 动词+ 不定式
afford aim appear agree arrange ask be decide bother care choose come dare demand desire determine expect elect endeavor hope fail happen help hesitate learn long mean manage offer ought plan prepare pretend promise refuse seem tend wait wish undertake
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+不定式 ； 动词+宾语+不定式
ask, beg, choose, expect , hate, help intend like, love, need prefer, prepare, promise, want, wish…
I like to keep everything tidy. 我喜欢每件东西都保持整洁。
I like you to keep everything tidy. 我喜欢你年使每件东西都保持整洁。
I want to speak to Tom. 我想和汤姆谈话。
I want you to speak to Tom. 我想让你和汤姆谈话。
3） 动词+疑问词+ to
decide, know, consider forget, learn, remember, show, understand, see, wonder, hear, find out, explain, tell
Please 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。
7.1 不定式作宾语
1) 动词+ 不定式
afford aim appear agree arrange ask be decide bother care choose come dare demand desire determine expect elect endeavor hope fail happen help hesitate learn long mean manage offer ought plan prepare pretend promise refuse seem tend wait wish undertake
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+不定式 ； 动词+宾语+不定式
ask, beg, choose, expect , hate, help intend like, love, need prefer, prepare, promise, want, wish…
I like to keep everything tidy. 我喜欢每件东西都保持整洁。
I like you to keep everything tidy. 我喜欢你年使每件东西都保持整洁。
I want to speak to Tom. 我想和汤姆谈话。
I want you to speak to Tom. 我想让你和汤姆谈话。
3） 动词+疑问词+ to
decide, know, consider forget, learn, remember, show, understand, see, wonder, hear, find out, explain, tell
Please 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。
7.2 不定式作补语
1) 动词+宾语+不定式(to do)
advise allow appoint believe cause challenge command compel consider declare drive enable encourage find forbid force guess hire imagine impel induce inform instruct invite judge know like order permit persuade remind report request require select send state suppose tell think train trust understand urge warn
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。
Find 的特殊用法：
Find 后可用分词做宾补，或先加形式宾语，再加形容词，最后加带to 的动词不定式。find后也可带一个从句。此类动词还有get，have。
I found him lying on the ground.
I found it important to learn.
I found that to learn English is important.
典型例题:
The next morning she found the man ___ in bed，dead.
A. lying B. lie C. lay D. laying
答案：A.find的宾语后面，用分词或分词短语，起宾语补足语作用。现在分词表达主动，也表达正在进行，过去分词表达被动。
2) to + be 的不定式结构，作补语的动词。
Acknowledge, believe, consider, think, declare(声称), discover, fancy(设想), feel find, guess, judge, imagine, know, prove, see(理解), show, suppose, take(以为), understand
We consider Tom to be one of the best students in our class.
我们认为汤姆是班上最好的学生之一。
典型例题
Charles Babbage is generally considered ___ the first computer.
A. to invent B. inventing C. to have invented D. having invented
答案：A. 由consider to do sth. 排除B、D。. 此句只说明发明这一个事实，不定式后用原形即可。而C为现在完成时，发明为点动词一般不用完成时，且此处也不强调对现在的影响，因此不选C。
3) to be +形容词
Seem, appear, be said, be supposed, be believed, be thought, be known, be reported, hope, wish, desire, want, plan, expect, mean…
The book is believed to be uninteresting.
人们认为这本书没什么意思。
4) there be+不定式
believe, expect, intend, like, love, mean, prefer, want, wish, undrstand
We didn’t expect there to be so many people there.我们没料到会有那么多人在哪里。
注意 ： 有些动词需用as 短语做补语，如regard, think believe, take, consider.
We regard Tom as our best teacher. 我们认为汤姆是我们最好的老师。
Mary took him as her father . 玛丽把他当作自己的父亲。
7.3 不定式主语
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 enough
It’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 you 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. 百闻不如一见。
(错)It is to believe to see.
7.4 It’s for sb.和 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. 对他来说学两门外语是很难的。
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, right。
It’s very nice of you to help me. 你来帮助我，你真是太好了。
for 与of 的辨别方法：
用介词后面的代词作主语，用介词前边的形容词作表语，造个句子。如果道理上通顺用of，不通则用for。如：
You are nice. (通顺，所以应用of)。
He is hard. (人是困难的，不通，因此应用for。)
7.5 不定式作表语
不定式可放在be动词后面，形成表语。例如：
My work is to clean the room every day.
His dream is to be a doctor.
7.6 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 a lot of work to do.
So he made some candles to give light.
7.7 不定式作状语
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. 他飞快地跑以便赶上第一班车。
I come here only to say good-bye to you. 我来仅仅是向你告别。
2）作结果状语，表事先没有预料到的，要放在句子后面。
What have I said to make you angry.
He searched the room only to find nothing.
3) 表原因
I’m glad to see you.
典型例题
The chair looks rather hard, but in fact it is very comfortable to ___.
A. sit B. sit on C. be seat D. be sat on
答案：B. 如果不定式为不及物动词，其后应有必要的介词。当动词与介词连用时，常位于"形容词+动词不定式"结构的末尾。
7.8 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
7.9 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。
I saw him dance.
=He was seen to dance.
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。
8） 由and, or和than连接的两个不定式，第二个to 可以省去：
9） 通常在discover, imagine, suppose, think, understand等词后，可以省去to be：
He is supposed (to be) nice. 他应该是个好人。
举例：
He wants to move to France and marry the girl.
He wants to do nothing but go out.
比较： He wants to do nothing but go out.
He wants to believe anything but to take the medicine.
典型例题
1) ---- I usually go there by train.
---- Why not ___ by boat for a change?
A. to try going B. trying to go C. to try and go D. try going
答案：D. why not 后面接不带to 的不定式，因此选D。
2） Paul doesn’t have to be made ___. He always works hard.
A. learn B. to learn C. learned D. learning
答案：B. make后接不带to 的动词不定式，当其用于被动时，to 不可省略。
7.10 动词不定式的否定式
Tell him not to shut the window…
She pretended not to see me when I passed by. 我走过的时候，她假装没看见。
典型例题
1）Tell him ___ the window.
A. to shut not B. not to shut C. to not shut
D. not shut
答案：B。 tell sb to do sth 的否定形式为tell sb not to do sth.
2) She pretended ___ me when I passed by.
A. not to see B. not seeing C. to not see
D. having not seen
答案：A。 pretend 后应接不定式。其否定形式为pretend not to do sth.。
3）Mrs. Smith warned her daughter ___ after drinking.
A. never to drive B. to never driver
C. never driving D. never drive
答案：A。warn sb to do sth. 的否定形式为warn sb not to do sth. 此处用的是否定词never.
4) The boy wanted to ride his bicycle in the street，but his mother told him ____.
A. not to B. not to do C. not do it
D. do not to
答案：A。not to 为not to do it 的省略形式。可以只用to这个词，而不必重复整个不定式词组。及物动词do后应有名词、代词等，否则不对，因此B，D不对。
5) The patient was warned ___ oily food after the operation.
A. to eat no B. eating not C. not to eat
D. not eating
答案：C。warn一词要求后用不定式，此处为不定式的被动，否定形式为be warned not to do。
7.11 不定式的特殊句型too…to…
1）too…to 太…以至于…
He is too excited to speak.
他太激动了，说不出话来。
---- Can I help you ? 需要我帮忙吗?
---- Well, I’m afraid the box is too heavy for you to carry it, but thank you all the same. 不用了。这箱子太重，恐怕你搬不动。谢谢您。
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)
改过不嫌晚。
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. 我非常高兴能帮助你。
He was but too eager to get home. 他非常想回家。
7.12 不定式的特殊句型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.
汤姆对事故保持沉默是为了不丢掉他的工作。
Go in quietly so as not to wake the baby.
轻点进去，别惊醒了婴儿。
2) so kind as to ---劳驾
Would you be so kind as to tell me the time?
劳驾，现在几点了。
7.13 不定式的特殊句型Why not
"Why not +动词原形"表达向某人提出建议，翻译为："为什么不……?" "干吗不……?"
例如：
Why not take a holiday?
干吗不去度假?
7.14 不定式的时态和语态
时态\语态 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) 现在时：一般现在时表示的动词，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. 我希望再见到你。
2) 完成时：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.
He seems to have caught a cold.
3) 进行时： 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) 完成进行时：
She is known to have been wreaking on the problem for many years.
7.15 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，意义相同。
3） 动名词与不定式语义不同的有11 组：
1 stop to do stop doing
2 forget to do forget doing
3 remember to do remember doing
4 regret to do regret doing
5 cease to do cease doing
6 try to do try doing
7 go on to do go on doing
8 afraid to do afraid doing
9 interested to do interested doing
10 mean to do mean doing
11 begin/ start to do begin/ start doing
情态动词
情态动词的定义:
情态动词是一种本身有一定的词义,表示说话人的情绪,态度或语气的动词,但不能单独作谓语, 只能和其他动词原形构成谓语。
We can be there on time tomorrow.
我们明天能按时去那儿。
May I have your name?
我能知道你的名字吗？
Shall we begin now?
我们现在就开始吗？
You must obey the school rules.
你必须遵守校规。
情态动词数量不多,但用途广泛,主要有下列:
can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would) .
情态动词的位置:
情态动词在句中放在谓语动词之前, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词则在主语之前。
I can see you. Come here.
我能看见你，过来吧。
He must have been away.
他一定走了。
What can I do for you?
你要什么？
How dare you treat us like that！
你怎能那样对待我们！
情态动词的特点:
情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加 "not"。 个别情态动词有现在式和过去式两种形式, 过去式用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去，现在或将来。
He could be here soon.
他很快就来。
We can't carry the heavy box.
我们搬不动那箱子。
I'm sorry I can't help you.
对不起，我帮不上你。
情态动词的用法:
can (could) 表示说话人能,可以,同意,准许,以及
客观条件许可,could 为 can 的过去式。
Can you pass me the books?
你能给我递一下书吗 ?
Could you help me, please?
请问,你能帮助我吗?
What can you do?
你能干点什么呢?
Can you be sure?
你有把握吗?
can 和could 只能用于现在式和过去式两种时态,将来时态用 be able to 来表示。
He could help us at all.
他完全可以帮助我们。
With the teacher's help,I shall be able to speak English correctly.
由于老师的帮助,我将能准确地讲英语。
may (might) 可以, 表示说话人同意,许可或请求对方许可。
You may take the book home.
你可以把书带回家去.
May I come in?
我可以进来吗?
May I use your dictionary?
我可以用你的词典吗?
You may put on more clothes.
你可以多穿点衣服.
He said he might lend us some money.
他说他可以借给我们一些钱。
may 否定式为 may not, 缩写形式是 mayn't.
might 是may 的过去式, 有两种用法, 一种表示过去式，一种表示虚拟语气, 使语气更加委婉, 客气或对可能性的怀疑。
He told me he might be here on time.
他说他能按时间来。
Might I borrow some money now.
我可以借点钱吗?
He might be alive.
他可能还活着。
Must 必须,应该,一定,准是, 表示说话人认为有必要做某事, 命令, 要求别人做某事以及对事物的推测。
must 用来指一般现在时和一般将来时, 过去式可用 have to 的过去式代替。
I must finish my work today.
我今天必须完成我的工作。
You mustn't work all the time.
你不能老是工作。
Must I return the book tomorrow?
我必须明天还书吗?
After such a long walk, you must be tired.
走了这么长的路,你一定困了。
He must be the man I am looking for.
他一定是我要找的人。
He had to go because of somebody's calling
him that day.
那天他要走是因为有人叫他。
must + have + 过去分词,表示现在对过去事物的推测。
He must have told my parents about it.
他一定把这件事情告诉我父母亲了。
He must have received my letter now.
他现在一定收到我的信了。
It's six o'clock already, we must have been late again.
已经六点钟了，我们一定又迟到了。
must 和 have to 的区别: must 表示说话人的主观思想, have to 表示客观需要。
You must do it now.
你必需现在就干。(说话人认为必须现在干)
I have to go now.
我得走了。(客观条件必须现在走)
need 需要 多用在否定式或疑问句中.
Need I attend the meeting tomorrow?
我需要明天参加会议吗?
You need not hand in the paper this week.
这一周你不必交论文。
need 是一个情态动词, 他的用法完全和其他情态动词一样, 但 need 还可当作实义动词使用, 这时 need 就象其他动词一样,有第三人称,单复数, 后面加带 to 的动词等特性。
I need a bike to go to school.
我上学需要一辆自行车。
Do you need a dictionary?
你需要词典吗?
She needs a necklace.
她需要一条项链。
needn't + have + 过去分词 表示过去做了没必要做的事情。
You needn't have taken it seriously.
这件事情你不必太认真。
dare 敢 多用在否定或疑问句中。
The little girl dare not speak in public.
小女孩不敢在公众面前说话。
Dare you catch the little cat?
你敢抓小猫吗?
dare 除用作情态动词外,更多的是当实义动词使用, 用法同实义动词一样,要考虑人称,单复数,时态等。
Do you dare to walk in the dark?
你敢黑夜走路吗？
He doesn't dare to tell the teacher what happened that day.
他不敢告诉老师那天发生的事。
ought 应当,应该 后面跟带有 to 的动词不定式。
You ought to read these books if you want to know how to repair the motorcar.
如果你想知道如何修理汽车,你应该读这些书。
You ought to bring the child here.
你应该把孩子带来。
ought + to have done 句型。指过去动作,表示一件事情该做而未做。
You ought to have been here yesterday.
你昨天就应该来。
ought not to have done 句型。表示一件不该做的事情却做了。
You ought not to have taken the book out of the reading-room.
你不应该把书带出阅览室。
will (would)决心,愿望。 would 为 will 的过去式,
可用于各人称。
I'll do my best to catch up with them.
我要尽全力赶上他们。
I'll never do it again, that's the last time.
我再不会做那件事情了,这是最后一次。
He said he would help me.
他说他会帮助我。
will, would用于疑问句表示说话人向对方提出请求或询问,用 would 比 will 更婉转,客气。
It's hot. Will you open the windows?
天气太热了,你能打开窗户吗?
Will you help me to work it out?
你能帮我解这道题吗?
Would you like some coffee？
给你来点咖啡怎样？
Shall, should表示命令,警告,允诺,征求,劝告,建议惊奇。
You should hand in the exercise book.
你应该交作业本儿了。
This should be no problem.
这应该没问题。
Shall we go now.
我们现在可以走了吗?
Why should I meet him？
为什么我要见他?
have to,不得不,必须,表示客观条件只能如此, 而must 则表示主观思想必须。
I have to go now.
我现在得走了。
I have to cook for my child.
我得给孩子做饭。
You must be here on time next time.
你下次一定要按时来。
We must go to get the timetable ourselves.
我们一定要自己去拿时刻表。
英语语法--动词不定式
动词不定式
7.1 不定式作宾语
1) 动词+ 不定式
afford aim appear agree arrange ask be decide bother care choose come dare demand desire determine expect elect endeavor hope fail happen help hesitate learn long mean manage offer ought plan prepare pretend promise refuse seem tend wait wish undertake
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+不定式 ； 动词+宾语+不定式
ask, beg, choose, expect , hate, help intend like, love, need prefer, prepare, promise, want, wish…
I like to keep everything tidy. 我喜欢每件东西都保持整洁。
I like you to keep everything tidy. 我喜欢你年使每件东西都保持整洁。
I want to speak to Tom. 我想和汤姆谈话。
I want you to speak to Tom. 我想让你和汤姆谈话。
3） 动词+疑问词+ to
decide, know, consider forget, learn, remember, show, understand, see, wonder, hear, find out, explain, tell
Please 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。
7.1 不定式作宾语
1) 动词+ 不定式
afford aim appear agree arrange ask be decide bother care choose come dare demand desire determine expect elect endeavor hope fail happen help hesitate learn long mean manage offer ought plan prepare pretend promise refuse seem tend wait wish undertake
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+不定式 ； 动词+宾语+不定式
ask, beg, choose, expect , hate, help intend like, love, need prefer, prepare, promise, want, wish…
I like to keep everything tidy. 我喜欢每件东西都保持整洁。
I like you to keep everything tidy. 我喜欢你年使每件东西都保持整洁。
I want to speak to Tom. 我想和汤姆谈话。
I want you to speak to Tom. 我想让你和汤姆谈话。
3） 动词+疑问词+ to
decide, know, consider forget, learn, remember, show, understand, see, wonder, hear, find out, explain, tell
Please 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。
7.2 不定式作补语
1) 动词+宾语+不定式(to do)
advise allow appoint believe cause challenge command compel consider declare drive enable encourage find forbid force guess hire imagine impel induce inform instruct invite judge know like order permit persuade remind report request require select send state suppose tell think train trust understand urge warn
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。
Find 的特殊用法：
Find 后可用分词做宾补，或先加形式宾语，再加形容词，最后加带to 的动词不定式。find后也可带一个从句。此类动词还有get，have。
I found him lying on the ground.
I found it important to learn.
I found that to learn English is important.
典型例题:
The next morning she found the man ___ in bed，dead.
A. lying B. lie C. lay D. laying
答案：A.find的宾语后面，用分词或分词短语，起宾语补足语作用。现在分词表达主动，也表达正在进行，过去分词表达被动。
2) to + be 的不定式结构，作补语的动词。
Acknowledge, believe, consider, think, declare(声称), discover, fancy(设想), feel find, guess, judge, imagine, know, prove, see(理解), show, suppose, take(以为), understand
We consider Tom to be one of the best students in our class.
我们认为汤姆是班上最好的学生之一。
典型例题
Charles Babbage is generally considered ___ the first computer.
A. to invent B. inventing C. to have invented D. having invented
答案：A. 由consider to do sth. 排除B、D。. 此句只说明发明这一个事实，不定式后用原形即可。而C为现在完成时，发明为点动词一般不用完成时，且此处也不强调对现在的影响，因此不选C。
3) to be +形容词
Seem, appear, be said, be supposed, be believed, be thought, be known, be reported, hope, wish, desire, want, plan, expect, mean…
The book is believed to be uninteresting.
人们认为这本书没什么意思。
4) there be+不定式
believe, expect, intend, like, love, mean, prefer, want, wish, undrstand
We didn’t expect there to be so many people there.我们没料到会有那么多人在哪里。
注意 ： 有些动词需用as 短语做补语，如regard, think believe, take, consider.
We regard Tom as our best teacher. 我们认为汤姆是我们最好的老师。
Mary took him as her father . 玛丽把他当作自己的父亲。
7.3 不定式主语
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 enough
It’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 you 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. 百闻不如一见。
(错)It is to believe to see.
7.4 It’s for sb.和 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. 对他来说学两门外语是很难的。
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, right。
It’s very nice of you to help me. 你来帮助我，你真是太好了。
for 与of 的辨别方法：
用介词后面的代词作主语，用介词前边的形容词作表语，造个句子。如果道理上通顺用of，不通则用for。如：
You are nice. (通顺，所以应用of)。
He is hard. (人是困难的，不通，因此应用for。)
7.5 不定式作表语
不定式可放在be动词后面，形成表语。例如：
My work is to clean the room every day.
His dream is to be a doctor.
7.6 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 a lot of work to do.
So he made some candles to give light.
7.7 不定式作状语
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. 他飞快地跑以便赶上第一班车。
I come here only to say good-bye to you. 我来仅仅是向你告别。
2）作结果状语，表事先没有预料到的，要放在句子后面。
What have I said to make you angry.
He searched the room only to find nothing.
3) 表原因
I’m glad to see you.
典型例题
The chair looks rather hard, but in fact it is very comfortable to ___.
A. sit B. sit on C. be seat D. be sat on
答案：B. 如果不定式为不及物动词，其后应有必要的介词。当动词与介词连用时，常位于"形容词+动词不定式"结构的末尾。
7.8 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
7.9 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。
I saw him dance.
=He was seen to dance.
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。
8） 由and, or和than连接的两个不定式，第二个to 可以省去：
9） 通常在discover, imagine, suppose, think, understand等词后，可以省去to be：
He is supposed (to be) nice. 他应该是个好人。
举例：
He wants to move to France and marry the girl.
He wants to do nothing but go out.
比较： He wants to do nothing but go out.
He wants to believe anything but to take the medicine.
典型例题
1) ---- I usually go there by train.
---- Why not ___ by boat for a change?
A. to try going B. trying to go C. to try and go D. try going
答案：D. why not 后面接不带to 的不定式，因此选D。
2） Paul doesn’t have to be made ___. He always works hard.
A. learn B. to learn C. learned D. learning
答案：B. make后接不带to 的动词不定式，当其用于被动时，to 不可省略。
7.10 动词不定式的否定式
Tell him not to shut the window…
She pretended not to see me when I passed by. 我走过的时候，她假装没看见。
典型例题
1）Tell him ___ the window.
A. to shut not B. not to shut C. to not shut
D. not shut
答案：B。 tell sb to do sth 的否定形式为tell sb not to do sth.
2) She pretended ___ me when I passed by.
A. not to see B. not seeing C. to not see
D. having not seen
答案：A。 pretend 后应接不定式。其否定形式为pretend not to do sth.。
3）Mrs. Smith warned her daughter ___ after drinking.
A. never to drive B. to never driver
C. never driving D. never drive
答案：A。warn sb to do sth. 的否定形式为warn sb not to do sth. 此处用的是否定词never.
4) The boy wanted to ride his bicycle in the street，but his mother told him ____.
A. not to B. not to do C. not do it
D. do not to
答案：A。not to 为not to do it 的省略形式。可以只用to这个词，而不必重复整个不定式词组。及物动词do后应有名词、代词等，否则不对，因此B，D不对。
5) The patient was warned ___ oily food after the operation.
A. to eat no B. eating not C. not to eat
D. not eating
答案：C。warn一词要求后用不定式，此处为不定式的被动，否定形式为be warned not to do。
7.11 不定式的特殊句型too…to…
1）too…to 太…以至于…
He is too excited to speak.
他太激动了，说不出话来。
---- Can I help you ? 需要我帮忙吗?
---- Well, I’m afraid the box is too heavy for you to carry it, but thank you all the same. 不用了。这箱子太重，恐怕你搬不动。谢谢您。
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)
改过不嫌晚。
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. 我非常高兴能帮助你。
He was but too eager to get home. 他非常想回家。
7.12 不定式的特殊句型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.
汤姆对事故保持沉默是为了不丢掉他的工作。
Go in quietly so as not to wake the baby.
轻点进去，别惊醒了婴儿。
2) so kind as to ---劳驾
Would you be so kind as to tell me the time?
劳驾，现在几点了。
7.13 不定式的特殊句型Why not
"Why not +动词原形"表达向某人提出建议，翻译为："为什么不……?" "干吗不……?"
例如：
Why not take a holiday?
干吗不去度假?
7.14 不定式的时态和语态
时态\语态 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) 现在时：一般现在时表示的动词，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. 我希望再见到你。
2) 完成时：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.
He seems to have caught a cold.
3) 进行时： 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) 完成进行时：
She is known to have been wreaking on the problem for many years.
7.15 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，意义相同。
3） 动名词与不定式语义不同的有11 组：
1 stop to do stop doing
2 forget to do forget doing
3 remember to do remember doing
4 regret to do regret doing
5 cease to do cease doing
6 try to do try doing
7 go on to do go on doing
8 afraid to do afraid doing
9 interested to do interested doing
10 mean to do mean doing
11 begin/ start to do begin/ start doing
情态动词
情态动词的定义:
情态动词是一种本身有一定的词义,表示说话人的情绪,态度或语气的动词,但不能单独作谓语, 只能和其他动词原形构成谓语。
We can be there on time tomorrow.
我们明天能按时去那儿。
May I have your name?
我能知道你的名字吗？
Shall we begin now?
我们现在就开始吗？
You must obey the school rules.
你必须遵守校规。
情态动词数量不多,但用途广泛,主要有下列:
can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would) .
情态动词的位置:
情态动词在句中放在谓语动词之前, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词则在主语之前。
I can see you. Come here.
我能看见你，过来吧。
He must have been away.
他一定走了。
What can I do for you?
你要什么？
How dare you treat us like that！
你怎能那样对待我们！
情态动词的特点:
情态动词无人称和数的变化, 情态动词后面跟的动词需用原形,否定式构成是在情态动词后面加 "not"。 个别情态动词有现在式和过去式两种形式, 过去式用来表达更加客气, 委婉的语气, 时态性不强, 可用于过去，现在或将来。
He could be here soon.
他很快就来。
We can't carry the heavy box.
我们搬不动那箱子。
I'm sorry I can't help you.
对不起，我帮不上你。
情态动词的用法:
can (could) 表示说话人能,可以,同意,准许,以及
客观条件许可,could 为 can 的过去式。
Can you pass me the books?
你能给我递一下书吗 ?
Could you help me, please?
请问,你能帮助我吗?
What can you do?
你能干点什么呢?
Can you be sure?
你有把握吗?
can 和could 只能用于现在式和过去式两种时态,将来时态用 be able to 来表示。
He could help us at all.
他完全可以帮助我们。
With the teacher's help,I shall be able to speak English correctly.
由于老师的帮助,我将能准确地讲英语。
may (might) 可以, 表示说话人同意,许可或请求对方许可。
You may take the book home.
你可以把书带回家去.
May I come in?
我可以进来吗?
May I use your dictionary?
我可以用你的词典吗?
You may put on more clothes.
你可以多穿点衣服.
He said he might lend us some money.
他说他可以借给我们一些钱。
may 否定式为 may not, 缩写形式是 mayn't.
might 是may 的过去式, 有两种用法, 一种表示过去式，一种表示虚拟语气, 使语气更加委婉, 客气或对可能性的怀疑。
He told me he might be here on time.
他说他能按时间来。
Might I borrow some money now.
我可以借点钱吗?
He might be alive.
他可能还活着。
Must 必须,应该,一定,准是, 表示说话人认为有必要做某事, 命令, 要求别人做某事以及对事物的推测。
must 用来指一般现在时和一般将来时, 过去式可用 have to 的过去式代替。
I must finish my work today.
我今天必须完成我的工作。
You mustn't work all the time.
你不能老是工作。
Must I return the book tomorrow?
我必须明天还书吗?
After such a long walk, you must be tired.
走了这么长的路,你一定困了。
He must be the man I am looking for.
他一定是我要找的人。
He had to go because of somebody's calling
him that day.
那天他要走是因为有人叫他。
must + have + 过去分词,表示现在对过去事物的推测。
He must have told my parents about it.
他一定把这件事情告诉我父母亲了。
He must have received my letter now.
他现在一定收到我的信了。
It's six o'clock already, we must have been late again.
已经六点钟了，我们一定又迟到了。
must 和 have to 的区别: must 表示说话人的主观思想, have to 表示客观需要。
You must do it now.
你必需现在就干。(说话人认为必须现在干)
I have to go now.
我得走了。(客观条件必须现在走)
need 需要 多用在否定式或疑问句中.
Need I attend the meeting tomorrow?
我需要明天参加会议吗?
You need not hand in the paper this week.
这一周你不必交论文。
need 是一个情态动词, 他的用法完全和其他情态动词一样, 但 need 还可当作实义动词使用, 这时 need 就象其他动词一样,有第三人称,单复数, 后面加带 to 的动词等特性。
I need a bike to go to school.
我上学需要一辆自行车。
Do you need a dictionary?
你需要词典吗?
She needs a necklace.
她需要一条项链。
needn't + have + 过去分词 表示过去做了没必要做的事情。
You needn't have taken it seriously.
这件事情你不必太认真。
dare 敢 多用在否定或疑问句中。
The little girl dare not speak in public.
小女孩不敢在公众面前说话。
Dare you catch the little cat?
你敢抓小猫吗?
dare 除用作情态动词外,更多的是当实义动词使用, 用法同实义动词一样,要考虑人称,单复数,时态等。
Do you dare to walk in the dark?
你敢黑夜走路吗？
He doesn't dare to tell the teacher what happened that day.
他不敢告诉老师那天发生的事。
ought 应当,应该 后面跟带有 to 的动词不定式。
You ought to read these books if you want to know how to repair the motorcar.
如果你想知道如何修理汽车,你应该读这些书。
You ought to bring the child here.
你应该把孩子带来。
ought + to have done 句型。指过去动作,表示一件事情该做而未做。
You ought to have been here yesterday.
你昨天就应该来。
ought not to have done 句型。表示一件不该做的事情却做了。
You ought not to have taken the book out of the reading-room.
你不应该把书带出阅览室。
will (would)决心,愿望。 would 为 will 的过去式,
可用于各人称。
I'll do my best to catch up with them.
我要尽全力赶上他们。
I'll never do it again, that's the last time.
我再不会做那件事情了,这是最后一次。
He said he would help me.
他说他会帮助我。
will, would用于疑问句表示说话人向对方提出请求或询问,用 would 比 will 更婉转,客气。
It's hot. Will you open the windows?
天气太热了,你能打开窗户吗?
Will you help me to work it out?
你能帮我解这道题吗?
Would you like some coffee？
给你来点咖啡怎样？
Shall, should表示命令,警告,允诺,征求,劝告,建议惊奇。
You should hand in the exercise book.
你应该交作业本儿了。
This should be no problem.
这应该没问题。
Shall we go now.
我们现在可以走了吗?
Why should I meet him？
为什么我要见他?
have to,不得不,必须,表示客观条件只能如此, 而must 则表示主观思想必须。
I have to go now.
我现在得走了。
I have to cook for my child.
我得给孩子做饭。
You must be here on time next time.
你下次一定要按时来。
We must go to get the timetable ourselves.
我们一定要自己去拿时刻表。
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