情态动词
一．情态动词基本用法
1.❶can和could，用在否定句和疑问句中,表示惊讶，用在否定句和疑问句中。
How could you do such a silly thing?
❷cannot....too/enough 表示“无论...也不过分，越...越好”。
You can’t be too careful while driving?
2.may和might的区别
❶表示许可、可能性、祝愿等意义，might比may更委婉。
A:给别人许可时。-May I play basketball this afternoon？
B:may/might as well+动原，“最好，倒不如”。
❷may作“可以”讲时，疑问句回答用mustn’t/can’t表示禁止。3. Must的用法
❶表示禁止（用于否定中）
You mustn’t smoke in the bedroom.
❷表示偏执、固执
-Could I have a word with you,mum? -Oh dear,if you must.
❸must的否定回答
A:作必须讲时，疑问否定回答用don’t have to,needn’t
B：推测，一定讲时，回答用can’t.
C:mustn’t表禁止。
--May I use your car? --No, you mustn’t./-Sorry,you’d better not.(委婉)
注意：must强调内在职责，而have to 强调迫于外界压力，不得已而为之。
4 .shall的用法
❶一、三人称征求意见时。请求对方时。Shall we begin our class?
❷二，三人称陈述句中，说话人给对方的命令，警告、允诺或威胁。
You shall not get my support if you do such a thing.
5.will和would的区别
❶自愿主动提出，如：意志、愿望或决心，would 过去，will not表示拒绝。
I have told him again and again to stop smoking,but he will not listen.
❷will习惯性动作，有“总是”或“总要”之意。
Everything he will have a walk along this year.
❸would过去习惯性动作，比used to 正式。
Last year our English teacher would sometimes tell us stories in English after
Class.
❹used to do 过去常，过去一直------只表示过去。
be used to do “用来”/be used to doing习惯于-----可表过、现或将。
6.dare表示敢于情态：dare do Dare you go home along？
及物：dare to do Do they dare to say what she thinks?
7.need用法情态：need do
及物need to do表示主动
need doing 被动My overcoats needs washing.
8. must一定要,必须，应该（现在时）
have to 客观需要，能用于更多时态（过去或将来）注意
ought to 表示义务和责任“应该”，比should语气强。
You ought to take care of yourself.
二．情态动词表推测用法
1.Sorry,I’m late,I might have turned off the alarm clock and go back again.
2.The accident could have been avoided.
3.You should have told me about it earlier.
4.You ought not to have said such words to your parents.
5.You needn’t have walked so quickly since time was enough.
6.He must have completed his work,otherwise,he wouldn’t be enjoying himself by seaside.
情态动词练习题
1.(2011全国卷II,8)If you ______ smoke, please go outside.
A. can
B. should
C. must
D. may
2.（2011北京卷,24）——I don’t really like James. Why did you invite him? ——Don’t worry. He ______ come. He said he wasn’t certain what his plans were.
A. must not
B. need not
C. would not
D. might not
3.（2011上海春招,27）some young people these days just ______ go out of their homes to contact the real world.
A. mustn’t
B. won’t
C. mightn’t
D. shouldn’t
4.（2011福建卷,25）——Shall I inform him of the change of the schedule right now?
——I am afraid you ______, in case he comes late for the meeting .
A.will
B.must
C.may
D.can
5.（2011安徽卷, 26）——What do you think of store shopping in the future?
——Personally, I think it will exist along with home shopping but _____.
A. will never replace
B. would never replace
C. will never be replaced
D. would never be replaced
6(2011浙江卷,11)——How’s your new babysitter?
——We ______ ask for a better one. All our kids love her so much.
