情态动词
【学习目标】
1. 掌握常见情态动词的意义及用法
2. 能够准确根据语境确定情态动词
情态动词有具体的词义，但也同助动词一样，需要与其他词语一起构成句子的谓语，另外情态动词没有人称和数的变化，
情态动词的类型
1.只作情态动词的有:must;can(could);may( might)
2.可作情态动词也可作实义动词的有need;dare
3.可作情态动词也可作助动词的有:will( would); shall( should)
4.具有情态动词某些特征的有: have to; had better; ought to
情态动词的特征
1.有一定的词义,但不能单独作谓语,必须和行为动词或系动词连用构成谓语, 情态动词后必须跟动词原形。
2.无人称和数的变化( have to例外,主语为第三人称单数时用 has to)。
如：He has to stay here.
【例题解析】
1. can 的用法：
(1).表示能力、许可、可能性。 表示能力时一般译为“能、会”， 即有这种能力，尤其是生来具备的能力，此时may 和must 均不可代替它。
如：She can swim fast, but I can’t .
I can see with my eyes.
(2).表示许可，常在口语中。
如：You can use my dictionary.
(3).表示推测，意为“可能”，常用于否定句和疑问句中， 此时can’t 译为“ 不可能”。
如：Can the news be true?
—Can it be our teacher?
—No, it can’t be our teacher. He is on a visit to the Great Wall.
2. could的用法：
(1).can的过去式，意为“ 能、 会”，表示过去的能力。
如：He could write poems when he was 10.
(2).could在疑问句中，表示委婉的语气，此时 could 没有过去式的意思。
如：Could you do me a favour?
—Could I use your pen?
—Yes, you can./Of course/Certainly
3. may的用法：
(1).表示请求、许可，意为“可以”比can 正式，
如：May I borrow your bike?
You may go home now.
may表示请求时,用于主语为第一人称的一般疑问句,其肯定回答用may回答；否定回答用 mustn't或cant,不用 may not,意为“不可以,不许,禁止”。
如：—May I go now?我现在可以走了吗?
—No, you must’nt./can’t不,不可以。
(2) .表示推测，谈论可能性，意为“ 可能， 或许”，一般用于肯定句中。
如：It may rain tomorrow .
明天可能会下雨。
She may be at home.
她可能在家呢.
(3) .may的过去式为might ，表示推测时。可能性低于may。
如：She is away from school. She might be sick.
她离开学校了，可能是她生病了。
(4) . 表示希望、祈求、祝愿，常可译为“祝愿”。通常是用may +主+V;
如：May you have a good time.
祝你过得愉快。
May you succeed！
祝你成功！
4. must的用法：
(1).must 表示主观看法，意为“必须、一定”。
如：You must stay here until I come back.
Must I hand in my homework right now?
对must引导的疑问句，肯定回答为must，否定回答为needn’t 或 don’t have to .
如：—Must I finish my homework?
—No, you needn’t.
(2) 其否定形式mustn’t表示“ 一定不要 ” “千万别” “禁止, 不许”.
如：You mustn’t play with fire.
You mustn’t be late.
(3)must表示有把握的推测，用于肯定句。
如: The light is on, so he must be at home now.
5. need的用法：
(1).need 表示需要、必须，主要用于否定句和疑问句中，其否定形式为needn’t，意为“没有必要，不必”。 用need 提问时，肯定会回答为 must，否定回答为 needn’t或don’t have to。
如：—Need I stay here any longer? 我还有必要留在这儿吗？
—Yes, you must .是的。
—No. you needn’t /don’t have to. 不， 你不必。
(2).need 还可以作实义动词，此时有人称、数和时态的变化，如果是人作主语后边多接动词不定式。
如：I need to do it right now.
He needs to learn more about the girl.
如果是物作主语，一般用need doing 与 need to be done这种情况下应注意两点：
①.主动形式的动名词doing具有被动的含义；
②.该动名词可以改为其动词不定式的被动形式而句子的意义不变。
如：The door needs painting. = The door needs to be painted.
那扇门需要油漆一下。
6. dare 的用法：dare意为“敢、敢于”, 用法近似于need，有两种词性：
(1).dare 作为情态动词，多用于否定句、疑问句或条件句中，无第三人称单数形式，只有一般现在时和一般过去时。如：Dare he tell them what he knows?
他敢告诉他们所知道的情况吗？
I daren’t ask her – will you do it for me?
我可不敢问她，你能帮我问问吗？
(2).dare 作为实义动词，此时有人称、数及时态的变化。
如：He doesn’t dare to break his promise.
他不敢食言。
7. shall 的用法：
shall表示征求对方意见（多用于第一人称）
如：Shall we go out for a walk?
我们出去散步好吗？
在英语中，我们可以用其他多种方式提出我们的建议或征求对方意见。
(1).用“Let's do…”来提出建议。
如：Let's go for a walk after supper.
(2).用“What/How about…?”来提出建议；about后接名词或动词ing形式。
如：What about/How about a drink? What about/How about taking Tom with us?
(3).用“Why not…?”来提出建议，表示“何不……”not面后接动词原形。实际上是“Why don't you/we…?”的简略形式。
如：Why not meet at the school gate at eight? Why don't we stay here another day?
(4).用“Would you like…?”来提出建议，意思是“你想要……吗?”Would you like后可接名词或不定式。
如：Would you like a cup of tea? Would you like to go and see her?
因此，如果我们说：“去游泳好吗?”英语中可有这样几种表达法：Shall we go for a swim? Let's go for a swim，shall we? What about/How about going swimming? Why not go for a swim? Would you like to go for a swim? What do you think of going for a swim?
8. should的用法：
(1).should 意为“应该” ，可表示劝告、建议、义务、责任等。
如：We should protect the environment.
我们应该保护环境。
(2).Should have done 表示对过去动作的责备、批评，意为“本该做但实际没做”。
如：You should have finished your homework.
你本应该已经完成作业了。（事实上你没有完成。）
9. will 的用法：
will表示意愿、意志、打算。
如：I will help you if I’m free this afternoon.今天下午如果我有空，我就会帮你。
注意：
1、will在there be句型中的形式及其句式变换。
由于“一般将来时”的结构可以用“will+动词原形”来表示，所以there be句型的一般将来时的形式就是there will be。（一定不能说there will have）
如： There are many students in our school. →There will be many students in our school.
There will be a sports meeting next week. 一定不能说：There will have a sports meeting next week.
2、will 与be going to do sth区别：
①. be going to 表示近期、眼下就要发生的事情，will 表示的将来时间则较远一些
如：He is going to write a letter tonight. He will write a book one day.
②. be going to 表示根据主观判断将来肯定发生的事情，will表示客观上将来势必发生的事情。
如：He is seriously ill. He is going to have a rest. He will be twenty years old.
③. be going to 含有“计划，准备”的意思，而 will 则没有这个意思，
如： She is going to lend us her book. He will be here in half an hour.
④.在有条件从句的主句中，一般不用 be going to, 而多用will
如：If any beasts comes at you, I'll stay with you and help you
10. had better 的用法：
had better 意为“最好”，没有人称的变化，后面接不带to 的不定式，其否定形式为：had better not。
如：We had better go now.
我们最好现在就走。
You had better not give the book to him.
你最好不要把这本书给他。
11.情态动词表示推测的用法:
（一） “情态动词+动词原形”表示对现在的推测。
(1).can表示推测时一般用于否定句或疑问句。
如：That man can’t be her husband she is still single.
(2).must表示肯定的推测，一般用于肯定句中。
如：He must be in his office now.
Mr Li must be working now, for the lights in his office are still on.
(3).might 表示推测时不一定是may的过去时，只是表示其可能性较小。
如：The man may be the headmaster.
—Where is Mr Li?
—He might be working in his office.
(4).Could表示推测时，语气can比要弱，说话者留有余地。
如：—Could it be an animal?
—It could not be.Because it is not moving.
（二）情态动词表示对过去可能发生的动作或存在过的动作的推测性用法。
(1).“must +have done/been——”表示“过去一定发生过某事或存在过某种状态”，不用于“musn’t+have—–”形式。
如：She must have seen the film before，hasn’t she?(注意反意疑问句的后半部分)
You must have met uncle Wang in the shop yesterday，didn’t you? ()
(2).“should +have done /been——-”表示“本应当做某事，而实际上并没有做”；
“ shouldn’t+完成式”表示“本来不应当做，而实际上却做了”。以上结构常带有说话者的责备的感情色彩。
如：You should have finished your homework earlier (but in fact you did not finish it on time).
You shouldn’t have gone to bed when you woke up at five (but in fact you went to bed again then).
(3).“needn’t+完成式”表示“本来没有必要做某事，而实际上却做了”。
如：There was plenty of time. She needn＇t have hurried .
(4).“can’t /couldn’t+have done /been——-”表示“过去不可能发生了某事或存在过某种状态”。
如：I saw him just now. He can’t have gone to Japan.
She said the man couldn’t have stolen her car.
(5)“could+have done/been——-”表示“过去本来能够，可以做某事或成为某种状态，而实际上没有”，说话者有些遗憾。“could sb. have done /been——-？”是它的问句形式。
如：You could have stayed with the Smiths while you were in New York (but in fact you stayed in a nearby hotel .) Could Mr Li have helped this girl student?
【演练】
1.You ________ stop when the traffic light turns red.
A. can B. had better C. need D. must
2.— Mum, must I stay there the whole day?
— No, you____________. You____________come back after lunch, if you like.
A. mustn't; can B. needn't; must C. needn't; can
3.“Whose notebook is this?” “It _______ Jim’s. It has his name on it.”
A. can’t be B. must be C. can be
4. There's enough time for you to go to the airport. You______ hurry now.
A. should B. needn't C. must D. can't
5.—Mum, must I wash the dishes right now?
—No, you ____.
A. shouldn’t B. wouldn’t C. mustn’t D. needn’t
6.—Is that your teacher?
—That_____be Mr.Wang. He has gone to Japan with his wife.
A. can’t B. mustn’t C. may not
7.— I swim here?
— I'm sorry. Children swim alone here.
A. Must; can't B. May; must C. Can; mustn't D. Can't; can
8. Lisa is a little poor at Chinese. I think she needs _____it every day.
A. practise to speak B. to practise speaking C. practise speaking
9.—Is that girl under the tree Mary?
—No, that ______be Mary. She is in New York.
A. can B. mustn’t C. can’t
10.— Shall we take a taxi?
— No, we . It’s not far from here.
A. can’t B. mustn’t C, shouldn’t D. needn’t
11.－You _____ be happy with the strong public support you’ve received.
－Yes,you"re right.I"m really excited.
A.may B.can C.must D.need
12. Tom, you _______ play with the knife．You______ hurt yourself．
A. won't; can't B. mustn't; may
C. shouldn't; must D. can't; should
13.―Jim, can you _______ this word in Chinese?
―Yes, I can_______ a little Chinese.
A. speak; say B. say; speak C. tell; speak D. talk; say
14.—My brother won the first prize in speech competition.
—Congratulations! You be excited about that!
A. need B. must C. would D. can
15.—Meng Fei had his arm broken while recording If You Are the One in Beijing.
—Really? Then perhaps he host TV programs for some time.
A. needn’t B. mustn’t C. shouldn’t D. can’t
16. –Have you decided which senior high school to choose?
–Not yet. I go to Moonlight School.
A. must B. may C. need D. should
17. —I hear you’ve got a new iPhone x. ______ I have a look?
—Yes, certainly.
A. May B. Do C. Shall D. Should
18. The lady in this photo be over fifty! She looks so young!
A. mustn’t B. must C. can’t D. can
19.—Excuse me, when are we going to have a picnic?
—I’m not sure, Ask our monitor, please. He know.
A. need B. can C. may D. shall
20.—I’m afraid I need a pair of glasses. I ____ hardly see the words on the blackboard.
—That’s terrible. You may have got poor eyesight.
A. can B. must C. may D. need
21. Last year I ______ drive. I used to take the bus.
A. could B. couldn’t C. should D. shouldn’t
22.In Britain, you ____ be 18 if you want to drive a car.
A.can B.must C.may D.might
23.—You be excited that you’re going back to your hometown soon.
—Yes, I can’t wait any longer.
A. shall B. can C. need D. must
24.—______ I try on those shoes in the window?
—______. They are just on show.
A. Could; Yes, you can B. Can; Sorry, you couldn’t
C. Could; Sorry, you can’t D. Can; Yes, you could
25. —Whose is the pencil box?
—It_______ be Tom's. Look at his name on the cover!
A. can B. may C. must D. need
26.—Do you have any plans for this weekend?
—I'm not sure. I ______ go climbing Mount Yuntai.
A. Must B. need C. may D. can
27. Many students come from poor families and they _____ afford school lunches, so the government is trying to help them.
A needn’t B. shouldn’t C. can’t D. mustn’t
28. _______ you dance? We need some more actors for the talent show.
A. Need B. Shall C. Must D. Can
