情态动词的基本用法
情态动词本身虽有一定的意义，但它必须和实义动词一起构成谓语动词，表示说话人的语气和情态，情态动词后接动词原形。初中学过的情态动词有can, could, may, must, need, shall, should, will, would, have to等。
1. can / could
表示能力（等于be able to）或客观可能性；还可以表示请求或允许；用在否定句、疑问句或感叹句中还可以表示惊异、怀疑、不相信的态度。Can / Could I ...? 表示请求对方许可（用could比用can语气更加委婉和客气，但答语必须用can）；Can / Could you ...? 用来表示说话人征求对方意见（用could比用can语气更加委婉和客气）。
2. may
表示许可或允许，意为“可以”。May I ...? 表示征求对方许可，否定回答一般用mustn’t或can’t。
3. must
意为“必须、应当”，表示义务、命令或必要；在回答must引出的问句时，肯定回答用must，否定回答用needn’t 或don’t have to，表示“没有必要”。
4. need
作情态动词时，多用于否定句或疑问句中，表示“需要”或“必要”（need用于肯定句时，常作实义动词，有人称和数的变化）。
5. shall
表示说话人征求对方的意见或向对方请示。
6. should
意为“应该”，表示义务、责任，可用于各种句式。
7. will
用于疑问句中，表示说话人向对方提出请求或建议；还可以用来表示做某事的意志、意愿、决心或打算。
8. would
表示过去的习惯性动作，有“总是、常常”的意思；还可表意愿、拒绝、请求等。
9. have to
意为“不得不”，强调客观需要，能用于多种时态；而must强调说话者的主观看法，没有时态变化。
【专项练习】
Ⅰ. 请从各题后所给的A、B、C、D四个选项中选出最佳答案。
( )1. —Must we clean the classroom now?
—No, you___________.
A. must B. needn’t C. should D. can’t
( )2. You____________ be careful with fire when you have a picnic in the forest.
A. will B. must C. can D. may
( )3. —May I go surfing alone, Dad?
—No, you____________. It is dangerous.
A. may not B. can’t C. needn’t D. don’t
( )4. —Should I call Mary here right away?
—No, you____________ . She is on the way here.
A. mustn’t B. can’t C. may not D. needn’t
( )5. — __________ you mind closing the door?
—No, not at all.
A. Would B. Can C. May D. Should
( )6. I said I _________do anything for him.
A. would B. will C. have to D. need
( )7. —It’s a secret between us. Don’t tell anybody else.
— ____________.
A. I do B. I don’t C. I will D. I won’t
( )8. —You must come to the meeting on time.
—OK, I _____________.
A. must B. have to C. will D. should
( )9. At the age of seven, I ____________speak a little English.
A. have to B. could C. can D. should
( )10. Many of the stars___________, because they are far away from us.
A. may not see B. can’t be seen
C. mustn’t be seen D. needn’t see
( )11. —Could I call you by the first name?
—Yes, you _____________.
A. will B. could C. might D. can
( )12. —Must I return the book tomorrow morning?
—No, you____________ . You __________ keep it for three days.
A. mustn’t; may B. mustn’t; must
C. needn’t; can D. needn’t; must
( )13. —May I go out to play basketball, Dad?
—No, you __________. You must finish your homework first.
A. mustn’t B. may not
C. couldn’t D. needn’t
( )14. —Can you go swimming with us this afternoon?
—Sorry. I ____________look after my little sister at home.
A. can B. may C. would D. have to
( )15. —Would you like to go fishing with me this afternoon?
—I’d love to, but I’m afraid I__________ . I have too much work to do.
A. can’t B. mustn’t C. needn’t D. may not
( )16. —What a nice day! __________we go hiking?
—Good idea.
A. Shall B. Must C. Need D. Will
( )17. We__________ keep the new traffic law and learn how to protect ourselves.
A. may B. should C. can D. could
( )18. —Must I come at four?
—Oh, no, you ___________.
A. don’t B. mustn’t C. don’t have to D. can’t
( )19. ___________ you get me some paper, please?
A. Shall B. May C. Need D. Will
( )20. —May I put my bike here?
—No, you ___________. You __________put it over there.
A. may not; may B. needn’t; must
C. mustn’t; should D. won’t; should
Ⅱ. 请按要求完成下列各句，每空一词（含缩写）。
1. My brother can play chess. （改为一般疑问句）
__________ _____________ brother _____________chess?
2. You should do the dishes. （改为否定句）
You___________ ____________ the dishes.
3. Could I open the window? （作肯定回答）
______________ , ___________ ____________.
4. May I smoke here? （作否定回答）
__________, __________ ___________ .
5. He must do it himself. （改为同义句）
He __________ __________ __________ it himself.
6. My sister can ride a bike.
（用when she was 10 years old改写句子）
My sister _________ __________ a bike when she was 10 years old.
7. You must sell your car. （改为一般疑问句并作肯定和否定回答）
____________ ____________ sell my car?
Yes, you _____________. / No, you_____________ .
8. The boy is able to write with his left hand.（改为同义句）
The boy ___________ ___________ with his left hand.
参考答案
情态动词的基本用法专项练习
Ⅰ. 1-5 BBBDA 6-10 ADCBB 11-15 DCADA 16-20 ABCDC
Ⅱ. 1. Can your, play 2. shouldn’t do 3. Yes, you can
4. No, you can’t / mustn’t 5. has to do
6. could ride 7. Must I; must; needn’t 8. can write
情态动词表示推测
【要点提示】
情态动词表示推测是其重要用法之一。可用来表示推测的情态动词主要有must, can / could, may / might等。
肯定推测：
must, can / could, may / might都可以表示肯定推测。must 表示把握性极强的推测，意为“肯定、一定”；can / could和 may / might表示把握性不大的推测，意为“也许、可能”。
否定推测：
can’t 意为“不可能”，表示很有把握的否定推测，may not意为“可能不”，表示把握性不太大的否定推测。
【专项练习】
Ⅰ. 请从各题后所给的A、B、C、D四个选项中选出最佳答案。
( )1. A teacher __________also make a mistake if he or she is not careful enough.
A. must B. may C. should D. has to
( )2. —What are you going to eat for supper?
—I__________ have noodles or rice.
A. need B. must C. may D. should
( )3. —Where’s Lucy?
—I’m not sure. She_________ be in the school library.
A. need B. must C. may D. will
( )4. —Look! Mr King is on the other side of the street.
—It ___________be him. He has gone to Lanzhou.
A. mustn’t B. can’t C. shouldn’t D. won’t
( )5. Hurry up! Dad __________for us at the train station.
A. must wait B. must be waiting C. need wait D. need be waiting
( )6. —Tom. Don’t drive too fast. You ___________hit the others’ cars.
—OK, I won’t, Mum.
A. must B. need C. might D. have to
( )7. —Whose book is this?
—It ___________be Peter’s. He entered the classroom just now.
A. need B. could C. should D. will
( )8. —There _________ many animals in the park.
—You are right.
A. has to B. have to C. may have D. may be
( )9. —You mean this CD __________ belong to Victor?
—Yes, it has his name on it.
A. must B. may C. might D. can
( )10. —There’s somebody at the door. It __________be Jim.
—It ___________be him. It’s just seven o’clock. It’s too early.
A. can; can’t B. will; won’t
C. should; mustn’t D. need; may not
Ⅱ. 请根据句意，从方框中选择适当的单词填空。
must, may, can’t
1. Such a businessman __________ be honest. He gets his money in such a dishonest way.
2. Mary’s parents have bought a large house with a swimming pool. They
__________ be very rich.
3. —Excuse me, is this the right way to No. 10 Middle School?
—Sorry, I’m not sure. It ___________be.
参考答案
情态动词表示推测专项练习
Ⅰ. 1-5 BCCBB 6-10 CBDAA
Ⅱ. 1. can’t 2. must 3. may
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