情态动词must、can、could、may、might精解.doc

would ： 1. 表will的过去,用于过去将来时
2. 表"意愿",乐意做某事
3. 虚拟语气
could: 1. 表can的过去,表过去的能力
2 表请求(婉转语气)
3. 表猜测:可能是...
4. 虚拟语气
should: 1. 表shall的过去,用于过去将来时,搭配第一人称
2. 表婉转的语气: 应该做...
3. 虚拟语气
might: 1. may的过去,表猜测:可能是
2. 表许可(婉转语气)
may: 1 表猜测: 可能是
2. 表许可
think of 想起, 想到; 没有think from的用法 一．
shall和will的用法
1、shall 用在第一、三人称，will 用于第二人称表示“征求意见”。
Shall I go now?
Shall we invite her, too?
Will you help me with the work?
Shall the reporters wait outside or what?
2、shall表示依据规定有义务去做。
Passengers shall not talk with the driver while the bus is moving.
3、shall 用于所有人称，表示说话人的许诺、威胁、警告、命令等。
You shall have an answer by tomorrow.
If he’s good, he shall have a new watch for Christmas.
If you children don’t do as I tell you, you shan’t go to the party.
4、would 可以表示过去的习惯（would 可表示反复发生的动作或某种倾向。used
to表示过去的习惯动作或状态，强调现在已不存在）
He would come to see me on Sunday when he was here.
The dog would lie there in the sun all afternoon.
When we were children, we would go skating every winter.
5、will可以表示“愿意”，而非将来:
I will pay you for it. 我会付给你钱买下它的。
Go where you will. 到你愿意去的地方。
We’re going on a climbing trip. Come if you will.
6、will可以表示倾向、习惯（总是会，老是等意思）
Sometimes the cat will lie there all morning.
Oil and water will not mix.
This machine won’t work.
二、can/could 的用法
1、表示具备某种能力。

The nine-year old boy can swim across the river.
Can you swim across the river?
We couldn’t get the truck to start.
2、表示“征询对方意见”和“允许”（could 语气委婉）。回答不用 could.
Can /could I smoke here? Yes, you can. No, you cannot.
Could you tell me where John is?
3、表示“可能性”。（否定句疑问句常见,肯定句也可以）
Can/Could it be true? 那会/可能是真的。
That can’t/couldn’t be true. 那不可能是真的。
Will you answer the phone? It could be your mother.
三．may/might 的用法
1、表示“征询对方意见”和“允许”。
May I turn on the TV?
Yes, of course. Yes, you can/may.
No, you can’t/may not /mustn’t /I’m afraid not.
You may go home now.
2、表示可能性，“也许”。常用于肯定句。
You may/might have some fever. 你也许发烧了。
He said that the news might be true. 他说这消息可能是真的。
They may/might be having a bath. 他们也许正在洗澡。
四．must的用法
1、表示“必须
Patients must use medicine according to the doctor’s orders.
2、表示推测，只用于肯定句。在否定句或疑问句中，用can/could：
There must be a mistake.
Can/Could there be a mistake
There can’t/couldn’t be a mistake.
He must be over sixty now.
They must be watching the news now.
They can’t/couldn’t be watching the news now.
3、注意must 的回答：
Must the ladies wear dresses?
yes, they must. No, they don’t have to. / they needn’t.
Can/May I come in? No, you can’t / mustn’t.
4．表示禁止。
Children mustn’t go across the street alone.
五．表示“推测”的表达法总结
（1）表示对现在和将来状况的推测：must 一定，may 可能，might 也许，can’t
不可能。
（2）对已经过去的情况的推测，用“情态动词＋have+ done”结构：
① must have done 过去一定已经…（只用于肯定句中）
② can’t / couldn’t have done 过去不可能--- （表示否定）

③ may/might have done 可能已经----
④ needn’t have done 本来不必做---
⑤ could have done那时本来可以…（在肯定句中，不可用can)
⑥ should have done 本来应该做---（实际未做）
⑦ shouldn’t / oughtn’t to have done 本不应该做-----（实际做了）
例如：
He must have been drinking beer. 他肯定一直喝啤酒来着。
The money can’t have been lost there. 钱不可能是在那儿丢的。
He may have gone to bed. 他可能已经上床睡觉了。
She might not have settled the problem. 她可能尚未解决那个问题。
We could have solved the problem in a more reasonable fashion.
You should have come here ten minutes earlier.
She should / ought to have gone there alone.
六、need的用法
1、作为情态动词，need一般只用于否定句和疑问句中。
You needn’t try to explain. Need we stay here this evening?
2、Need 作为实意动词可用在所有句型中。
She needs to come tomorrow.
You don’t need any help from others. Do they need this?
七、dare的用法
1．做情态动词，通常用于疑问句，否定句和条件状语从句中。
Dare he swim across the river?
He dare not come to see me.
How dare you be so rude! 你竟敢如此无礼！
2．做实意动词：
Do you dare to ask her? 你敢问她吗？
He didn’t dare to go. 他不敢去。
八．should/ought to的用法
两者大多数情况下可以互换。
1、表示道义上的责任，义务或要求，有时表示劝告。如：
You ought to /should pay more attention to what your lawyer says.
This word is spelt wrongly. There should be another “s”.
2. 表示推测和可能性，是“应该”之意。
This pen ought to /should be yours. 这支笔应该是你的。
If the train is up to time, John should/ought to be here any minute now. 如果火
车晚点的话，John现在马上就应该到了。
3、表示讲话人惊奇，失望，愤怒等感情：
What’s happened to that money? How should I know? 那些钱怎么了？－我怎
么知道？
It’s strange that he should have lost his temper for such trivial things as that.
真奇怪，他竟然为这么小的事情发脾气。
Why should I believe you? 我为什么要相信你？
think of
v.
考虑, 关心, 想起, 想象, 有...的看法, 记起

think of
think of (about),dream of (about)
think of (about) 可以用来表示对问题的看法或考虑某件事：
表示“认为”时，不用进行时态
I think of it as impossible.
我认为这是不可能的。
What do you think about it?
你认为这件事怎么样？
I think that the doctor had better see you.
我想最好还是请医生来看看你。
表示计划或想法时可以用进行时态。
She threw the bottle into the sea. She never thought of it again.
她把那只瓶扔进海里，从未再想起它。
I'm thinking of going to university next year.
我在考虑明年上大学。 dream of (about)的含义是“考虑那些自己认为不会发生的事”，这时应当用介词
of，在表示“梦中看到什么”时，通常用about。
表示梦中见到。
I dreamed about you last night.
我昨夜里梦到你了。
He often dreams about home.
他常常梦到家乡。
当用来表示“想到”时，通常用of
I never dreamed of happiness like this.
我过去做梦也没想到象这样幸福。
My daughter, Jane, never dreamed of receiving a letter from a girl of her own
age in Holland.
我的女儿珍尼过去做梦也没想到会收到与她年龄的一位荷兰姑娘的来信。
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think about
v.
考虑, 回想 情态动词must, can, could, may, might表推测的用法：情态动词中的must, can, could, may, might都表推测。其中must的可能性最大，can / could次之，may / might最小。具体用法如下：
1. must的用法
（1）表示推测“可能性”时，意思是“一定、准是”，语气较肯定，较有把握。
He must be American. = It is certain that he is American. 他准是个美国人。
（2）must表推测只能用于肯定句。如果要表示“一定不、肯定不”的意思时，应用can`t,如询问某种可能时，应用can。
He must know my address. 他肯定知道我的地址。（一定）
He can`t know my address. 他肯定不知道我的地址。（一定不）
Can he know my address? 他知道我的地址吗？（询问可能性）
（3）must表示推测时，可以推测现在/正在发生的动作/过去发生的动作。
He must have a car now. （现在）他一定有辆小汽车。
He must be doing his exercises in the classroom.（正在进行）他一定在教室里做练习。
He must have finished the work.（过去发生）他一定已完成了工作。
注：must表示推测时很少用于将来的情况。一般不用He must come tomorrow.可用It`s certain / I`m sure that he will come tomorrow.
（4）在反意疑问句中，当附属部分含有表示推测意义的must时，疑问部分的助动词应与must后面的动词在非推测情况下的用法保持一致。
He must be a worker, isn`t he? （现在）他准时个工人，是吗？
It must have rained last night, didn`t it? （过去）昨晚一定下雨了，是不是？
You must have learned English for many years, haven`t you? （完成时）你一定学了好多年英语，是吗？
2. can / could的用法
（1）can表示推测“可能性”时，往往用于否定句或疑问句。Can`t“一定不”，语气很肯定。can在疑问句中意思是“会、可能”。
He can`t be at home. = It is impossible that he is at home. 他一定不在家。
（2）can /can`t后可接进行时/完成时，表示对现在发生的动作或过去发生的动作进行推测。
They can`t be reading in the library. 他们一定不在图书馆读书。
He can`t have gone to Shanghai for I saw him a minute ago.
他不可能去了上海，我刚才还看见他。
It`s so late. Where can she have gone? 天晚了，她可能去哪儿了呢？
（3）在反意疑问句中，当陈述部分含有表示推测意义的can`t时，疑问部分的助动词应与can`t后面的动词在非推测情况下的用法保持一致.
He can`t be a teacher, is he? 他不是教师，是吗？
She can`t have finished her homework, has she?
她一定没有完成家庭作业，是不是？
（4）could可用于表示某事有可能发生或可能是事实。
Don`t eat it. It could be poisonous. 不要吃它，可能有毒。
The plane could be delayed by fog. 飞机可能会因为雾晚点。 （5）could还可以用于表示客气、委婉、礼貌的请求语气。
Excuse me, could you tell me the way to the bus station?
Could you help me?
（6）couldn`t表示否定推测，表示某事不可能真实，或由于特定事实或环境某事肯定不会发生。
It couldn`t possibly be poison. 这不可能是毒药。
注：有时与形容词的比较级连用强调某人或某物不可能再更多地具有某种属性。
You couldn`t be more wrong. 你真是大错特错。
I couldn`t be happier. 我简直是幸福极了。
3. may和might的用法
（1） may, might表示推测“可能性”时，意思是“可能”、“也许”，语气没有 must肯定。
He may / might be American. = It is possible that he is American.
他可能是个美国人。
注：might不表示过去时态，只是语气上比may更委婉，表示的可能性更小。
（2）may, might表推测时，可以用于否定句，意思是“可能不、也许不”，但不用于疑问句。
He may / might not be at home. 他也许不在家。
（3）may, might可以推测现在正在发生的动作或过去发生的动作。
He may / might be sleeping now. （现在）他可能正在睡觉。
The boy may / might not be watching TV at home. （现在）
这个男孩可能没在家看电视
These students may / might have seen the film before.（过去）
这些学生以前可能看过这部电影。
（4）may, might还可以推测将来的情况。
I think we should take raincoat with us, it may rain.
我想我们应该带上雨衣，可能要下雨了。
She might not come this afternoon. 她今天下午可能不来了。
Exercises: Complete the sentences using“must”or“can`t”.
1. I have tried to call him at the office, but there is no reply. He be at home.
2. They have bought a new car. They have a lot of money.
3. She is carrying a Japanese newspaper. She be Chinese.
4. He goes abroad a lot, He have an important job.
5. She is a professor at the university. She be very clever.
6. She is acting in a Shakespeare play tomorrow. She be an actress.
一. Choose the best answers to complete the following sentences:
1. I thought you like something to read. So I have brought you some books.
A. ought B. might C. could D. must
2. –That man must be Sarah`s husband.
--No, he be her husband. She is still single.
A. can`t B. mustn`t C. may not D. ought to
3. Peter come with us tonight, but he isn`t very sure.
A. must B. may C. can D. will
4. –What it be?
--It be a mail box, for it is moving. It be a car.
A. can; can`t; must B. can; can; must
C. can; mustn`t; must D. must; mustn`t; can
5. –Look, someone is coming. Guess .
--Jack. He`s always on time.
A. who can it be B. who he may
C. who he can be D. who it can be
6. –I saw Mary in the library yesterday.
--You her. She is still abroad.
A. mustn`t see B. can`t have seen
C. mustn`t have seen D. couldn`t see
7. David, you play with the valuable bottle, you break it.
A. won`t; can`t B. mustn`t; may
C. shouldn`t; must D. can`t; shouldn`t
8. Susan refuses to marry Jack now. She her mind.
A. must change B. should have changed
C. must have changed D. would have changed
9. Sue come together with us tonight, but she isn`t very sure yet.
A. must B. may C. need D. will
10. Aunt Margaret the rain, otherwise she would have arrived here by now.
A. must have missed B. should have missed
C. had missed D. might miss
二. Fill in the blanks using must / can / could / may / might and their negative forms.
1. –Could I borrow your dictionary?
--Yes, of course you .
2. She doesn`t answer the bell. She be asleep.
3. The ground is wet. It have rained last night.
4. He is writing with a pencil. He have lost his pen.
5. A computer think for itself, it be told what to do.
6. There is much gas here, you smoke here.
7. –Was he present at the meeting?
--He not have attended it, for he was busy repairing his car all the time.
8. Look! An old man is lying in the middle of the street. He be hurt in an accident.
9. Nobody saw her at the meeting yesterday, she have spoken at the meeting
10. –My goodness. I just missed the train.
--That`s too bad. I am sure you have caught it, if you had hurried.