情态动词的用法及专项练习
情态动词的用法
．分类：
1. 只做情态动词：
can（could）、may（might）、must 后接动词原形。
2. 可做情态动词又可做实义动词。如：need，dare
3. 具有情态动词特征：
have （has, had）to , used to （过去常常）。
二．情态动词的用法：
情态动词后接动词原形
1. m ust 的用法
1）m ust 意为“必须；应该；一定”。表示说话人的主观意志,表示必须要做的。如：
We must fin ish readi ng the book in two weeks .我们必须在两周内看完这本书。
2）表示说话人对事物的推测,语气比may 肯定,只用于肯定句中。Must be 译为“一定是”如：
Mr. Liu must be in the office.刘老师一定在办公室。
3）用must提问时，如果是否定回答，多用needn '或don' t have to表示不必，没必要”，而mustn '表示绝对不行，不可以，禁止”的意思。如：---Must I finish my homework now?
---Yes,you must.---No,you needn ' t/don ' t have to
4) have to 意为“必须；不得不”，有人称、时态和数的变化，后跟动词原形，表示客观需要。如：
When I was your age，I already had to work.
2. c an 的用法：
1) can意为能；会；可以”。表示能力，其否定式是cannot二can。如：
She can si ng她会唱歌。
2) 表示请求许可。Can I ...臆思是我可以??…吗？”，较口语化。
3) can的过去式是could，如：
Lucy could swim at the age of five 露西五岁时就会游泳了。
could 也可表示较can 更为委婉的语气。如：
Could you help me?帮帮我好吗？
4) can表示推测时，常用于否定句和疑问句中。Can' tb不可能是”，若是疑问句，其肯定回答用may或must。
如：
—Where can it be?它会在哪里呢？一It may/must be in your desk .它可能/ 一定在你的课桌里。
否定回答：
It can ' t be in your c它不可能在你的课桌上。
3. m ay的用法：
1) may 意为“可以；可能”。表示请求、许可。
如：
May I look at your CD player?我可以看一下你的CD机吗？
2）表示可能性（说话人的猜测），常用于肯定句中。如：
Your sister may be wait ing for you now.你妹妹可能现在正在等你呢。
3）以may 引起的一般疑问句，否定回答多用mustn '；t
4. need 的用法：
1） need 作情态动词时，意为“需要”，后接动词原形，常用于疑问句和否定句中，否定形式：
needn '疑问句：
Need 提前如：
You needn ' t try to explain.
Need I explain it?
2） need作为实义动词时，后接动词不定式to do，有人称和数的变化。如:
He（不需要）borrow money.
Do they ______ （需要）do homework today？
5. had better 的用法：
had better（not）do sth 最好（不要）做某事
如：
You' d better ___ （stay） at home.
You' d better ____ （not watch） TV.
练习：
A. may
B. can
C. has to
D. must
( ) 2 They ___ do well in the exam.
A. can be able to
B. be able to
C. can able to
D. are able to
( ) 3 -May I take this book out?
-No, you___.
A. can't
B. may not
C. needn't
D. aren't
( ) 4 You___ go and see a doctor at once because you're got a fever.
A. can
B. must
C. dare
D. would
( ) 5 -Can you speak Japanese?
-No, I
A. mustn't
B. can't
C. needn't
D. may not
( ) 1 -He___ be in the classroom, I think.
-No, he ___ be in the classroom. I saw him go home a minute ago.
A. can; may not
B. must; may not
C. may; can't
D. may; mustn't
( ) 2 -Shall I get one more cake for you, Dad?
-Thanks, but you___, I've had enough.
A. may not
B. must not
C. can't
D. needn't
( ) 3 Even the top students in our class can't work out this problem, so itbe very difficult.
A. may
B. must
C. can
D. need
( ) 4 He isn't at school. I think he ___ be ill.
A. can
B. shall
C. must
D. has to
( ) 5 ___ I take this one?
A. May
B. Will
C. Are
D. Do
( ) 1 The children___ play football on the road.
A. can't
B. can
C. mustn't
D. must
( ) 2 You ___ be late for school again next time.
A. mustn't
B. needn't
C. don't have to
D. don't need to
( ) 3 -Must I do my homework at once?
-No, you___.
A. needn't
B. mustn't
C. can't
D. may not
( ) 1 His arm is all right. He___ go and see the doctor.
A. has not to
B. don't have to
C. haven't to
D. doesn't have to
( ) 2 He had to give up the plan, ___ he?
A. did
B. didn't
C. does
D. doesn't
( ) 3 They had to walk here, ___ they?
A. mustn't
B. did
C. didn't
D. hadn't
( ) 1 He had better stay here, ___ he?
A. didn't
B. don't
C. hadn't
D. isn't
( ) 2 You'd better___late next time.
A. not to be
B. not be
C. won't be
D. don't be
( ) 3 You'd better ___ your hair ___ once a month.
A. had; cut
B. had; cutted