关于情态动词
一．基本用法：
1．can/could : （1）表能力 （2）常用于疑问句、否定句中，表示惊讶怀疑等。（3）表示客观事实汽车燃料 （4）表示推测，常用于疑问句、否定句中。（5）口语中表示请求允许，相当于“may社区工作者面试”. （6）could口语中可以表推测，用于肯定句，相当于”may”。
be able to: （1）表能力更侧重结果或表做某事的具体能力。（2）由多种时态
can 的过去式为could，但它通常只表示过去一般性能力，不表示过去特定场合下的能力，遇此情况要用 was [were] able to。如：
I could run faster then. 。They were able to jump into the a before the boat was blown up. 他们在船爆之前跳入海里。
e.g. How can you be so careless? （表惊讶） The wind can be strong at the top of the mountain.
绿豆排骨汤
Can I ask you a question? ( =may)
The fire spread so fast that few people were able to escape from it. (结果)
She has been able to talk to us in English.
注意：can’t …too/enough 意为“。。。不为过”, “很，十分”；
cannot (help) but do something. “ 禁不住做。。。，不得不，只得
e. g. You can never be careful enough. I can’t speak too highly of him.
I could (help) but admit that I was wrong.
2. may/might: （1）表示请求对方允许， 其否定回答为mustn’t/can’t （2）表示可能性的推测，常用于肯定句、否定句中（3）表示祝愿
e.g May I come in? ( No, you mustn’t/can’t. ) (土茯苓请求对方允许)
I’m not sure what I will do tonight, and I may go to the cinema. (( 推测)
May you succeed! ( 比较：I wish you success.)
3. must: （1）必须，表示说话人的主观看法，其否定回答常用needn’t/can’t/don’t have to ( 注意mustn’t 表示禁止)
（2）表示把握比较大的推测 意为“一定，想必”，只用于肯定句中。
（3）情态动词 must 有时可以表示固执、偏激或碰巧，通常可译为“偏偏”。如：
After I gave her my advice, she must go and do the opposite. 在我给她出主意之后她偏反着干。
The car must break down just we were starting our holidays. 我们刚刚开始休假，汽车偏偏坏了。
have to: （1）“不得不，只得”，表示客观需要，其否定式为：don’t/doesn’t/didn’t have to
（2）有现在时、过去时、将来时和完成时。
e.g. It must be Xiao Wang. (借月抒情的诗句推测 Why must it rain on Sunday? (偏偏)
Why must I do that? ( 同上) I’ll have to prepare dinner.
4. shall/should:（1）用于二、三人称的陈述句中，表示“警告、威胁、命令、允诺、强制”等
（2）用于一、三人的疑问句中，表示询问或征求对方意见。（3）should 表示推测， 意为 “按理应该…”
（4）should 表示惊讶、怀疑、出乎意料、理应如此等。
ought to :用法基本与should同，但更强调客观上的责任义务语气比should强
e.g. Shall he clean the window? (表示征求对方意见)
Everything shall be taken away if you break the law. (表示强制)
You shall have the book as soon as I finish reading it. (表示允诺)
It’s already ven o’clock. Jack should be here at any moment.( 推测)
It’s strange that you should have been fooled by such a simple trick. (惊讶)
5. will/would: （1）表示意愿，适用于各个人称（2）用于第二人称的疑问句中，表示征求对方意见。
（3）表示某种倾向。（4）would 表示过去的习惯（比较ud to do sth.）, 不可与表示状态或存在的词连用。
e.g. If you will wait for a minute, our manager will meet you. (表示意愿)
Will you plea repeat it?/ Would you like some fruit? (表示征求意见)
Fish will die without water. / Boys will be boys. (表示某种倾向)
When I was a child, I would always read at the window.( 过去的习惯)
There ud to be a stop at the corner. (表示存在汉语教程, 不能用would)
6. need （1）表示必要，常用于疑问句和否定句中，无人称、时态和数的变化。
（2）实义动词， 意为“必要，需要”，后面可接名词、代词、动名词和不定式。动名词表被动，不定式表主动。
dare: (1) 常用于疑问句、否定句和条件句中，只有现在时和过去时。（2）用作实义动词，后接不定式。
e.g. You needn’t pay for it., need you? (情态动词) He doesn’t need any help.（实义动词）
The door needs painting.（实义动词）You need to pay more attention to your pronunciation. （实义动词）
If you dare do that, you shall be punished. (情态动词)She stopped at the door, not daring to enter. (实义动词) 注意：I dare say 意为“可能，我相信”
7. had better ( not ) do something ( Had you better do something? )
would rather (not ) do something 如何算八字（Would you rather not do something?）
ud to do something ( Ud/Udn’t you to do something?)
二．关于推测
1．表示对现在动作的推测：肯定构成：must/may/might do 否定构成：may/can’t do something
疑问句： Can + S. do something?
e.g. He must/may/might be Xiao Wang. He can’t be at home now, is he?
2. 对过去动作的推测 肯定构成：must/may/might have done something
否定构成：may/might/can/could not have done something 疑问句 : Can/Could + S. have done something?
e. g. It must have rained last night, for it is wet on the ground.
He can’t have finished the work yesterday, did he?
例的形近字They may have been at home for a long time, haven’t they?
They must have learnt 3000 words by the end of last term, had they?
They can’t have been at home last night, were they?
3. 对进行动作的推测：
肯定构成: must/may/might be doing something 否定构成: may/might/can’t/couldn’t be doing something
e.g. He must be watching TV now.
