资源简介

情态动词
第一节 情态动词的基本用法
1 .can/could
1)能够(过去式:could.否定形式can’t/couldn’t:不能够）
Nobody can stop the development of science.
I can’t speak English, but I can speak some Spanish.
2)可能(不牵涉是否真的发生，客观存在的可能性）
Even expert drivers can make mistakes.
Mr. Reed is in poor health. He can be ill at any time.
用can表示“可能”，较多地用于否定句和疑问句，而could则不受此限
If you don’t have a guide, you could lose your way.
The moon cannot always be at the full.
What can he possibly mean
3)允许(can/could无时间上的差异，只是could较为婉转，更有礼貌）
You cannot leave here till I come back.
Anyone can enroll for this course.
4) can’t... too… /can’t… enough 再…也不为过
You can’t be too careful/ careful enough when driving.
We can’t put too much emphasis on cooperation.
2. may/might
1)或许，可能(指事实上的可能性，且might/may无时间上的差异，只是might在口气 上更加不确定，从而比较婉转）
I may be busy from tomorrow on.
You may catch sight of the sunrise from here when you get up before 5 in the morning.
He might be still waiting at your office.
在疑问句中表示“可能”，用can/could,而不用may/ might Where can he be
Can they be angry
may/ might not有“不可能”及“不允许”两种意思，故表示“不可能”时，常用 “can’t/ couldn’t”
This can’t be my handbag.
She can’t love Paul.
2) 表示允许，许可（might/may无时间上的差异，只是might较为婉转，更有礼貌）
May I come in
May I smoke here
3) may可以用来表示祝愿
May you succeed.
May you enjoy your holiday.
4) may/might (just) as well do不妨……，最好……
You may as well stay at home.
Since it’s a fine day, we might as well walk.
3. must
1) 法律/规定上要求的或道德上是必需的，出于职责、义务该做某事
Everyone must be loyal to his motherland.
All drivers must obey the traffic rules.
2) 表示出于主观意识而必须要做某事
We must keep steps to the scientific development.
You must hurry up, or you’ll be late.
3) must be表示猜测、推测，常用于肯定句中表示猜测 (否定:can’t be)
You must be tired after working so long.
The lights are on. They must be at home.
4) 表示禁止 (用于否定句）
You must not speak ill of others.
You mustn’t do anything illegal.
注意：mustn’t只表示“禁止”; 若需表示“不可能”，用can’t/couldn’t; 表示“不需要”，用 needn’t 或 don’t/doesn’t/didn’t have to
4. have to/has to/had to
1) 不得不
Animals kept in this way can easily get sick, so they have to be given drugs.
We will have to do it again.
5. should/ought to
1) 表示出于职责、义务该做某事，有时也表示“劝说”或“敦促”的含义
We ought to study hard for the sake of our motherland.
You should write to your parents at least once a month.
You should learn from each other.
He ought to drink less.
2) 表示根据一定情况作出的推测或推断
That shouldn’t be a difficult problem for Mary.
She should be here in a minute.
The book should appeal to all lovers of poetry.
These young trees ought to provide shade in ten years.
3) should可表示惊讶，失望等情绪，竟然
It seems so unfair that this should happen to me.
It’s a pity that he should leave so soon.
4) should用于名词性从句的虚拟语气
The doctor suggested that he should give up smoking.
The order that all civilians should be evacuated was soon carried out.
6. need (—般只用于否定句和疑问句）
不需要
I needn’t say how much we missed you.
We needn’t stay this evening.
Need I tell him at once
Need we work late today
7. dare/dared
敢 (一般只用于否定句和疑问句）
How dared you say that to her
I daren’t go there alone.
He dare not jump from the top of the wall.
The president was so hot-tempered that no one dare tell him the bad news.
8. used to (否定形式：didn’t use to或 usedn’t to)
表示过去习惯动作或状态
My colleague used to work as a receptionist in a hotel.
There used to be an old temple at the corner of the street.
He didn’t use to smoke cigarettes.
Maria usedn’t to have an interest in musicals.
9. shall (否定形式:shan’t)
shall用于第一人称
将来时
I shall be back in a minute.
I shall never do that again.
表示征求意见
Shall I go with you
Shall we go
shall用于第二、第三人称
表示说话人的意图
Tell Tom he shall have the book tomorrow.
You shall get a promotion.
表示说话人的强烈决心
That day shall come.
He shall leave the country at once.
规定 (按法律、条约、规章等必须履行的义务，相当于must)
Persons under 18 shall not be employed in night work.
Candidates shall remain in their seats until all the papers have been collected.
10. will/would
1) 用于第二人称疑问句，表示请求 (在这种用法中would使语气更为客气、委婉）
Will you tell her that I’ll be back in twenty minutes
Would you please do me a favor
用于表示愿望、意愿
Go where you will. 去你想去的地方吧。
You can help me if you will.
表示习惯、倾向（可译成“总是会，老是”）
Oil and water will not mix. 油和水决不能调和。(倾向)
He would sit there for hours, doing nothing at all. (习惯）
will用于表示决心 (可译成“一定要，决心”）
We will never talk about that subject again.
I will take the job and no one is going to stop me.
第二节 情态动词+ have done
表示对过去的推测
may/might/could have done →可能已经做了某事
must have done →肯定已经做了某事
can’t/couldn’t have done →不可能做了某事
You may/might/could have narrowly missed her on your way to school.
She may/might/could have been hurt in the volleyball game.
You must have talked about it with her beforehand.
Dora must have left her cell phone in the hotel.
You couldn’t have seen her in the bar because she was busy in her office yesterday night.
He can’t have been to your home. He doesn’t know your address.
注意: “can+完成式”一般只用于进行否定或疑问的推测
表示对过去的虚拟
might/could have done →本可能做却没做
should/ought to have done →本应该做却没做
shouldn’t/oughtn’t to have done →本不应该做却做了
needn’t have done →本不需要做却做了
The output might/could have been increased by 15%.
You might/could have finished the work last week.
They should/ought to have completed their work much earlier.
You should/ought to have asked my permission first.
You shouldn’t have been so rude to your parents.
You shouldn’t/oughtn’t to have cheated your tutor.
You needn’t have apologized to him yesterday.
She needn’t have rented that apartment.

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