What shall we do this evening?
注意：may用于征求对方的许可，而shall用于征求对方的意见或指示：
May I have a look?我能看一看吗?
Shall I have a look?需要我看一看吗?
You shall fail if you don’t work harder. (警告)
He shall have the book when I finish reading. (允诺)
He shall be punished.(威胁)
The fine shall be given in cash.罚款须以现金缴纳。
hould | 意义 |
①（表义务、责任的）应该 | |
②（表预期的）应该会，想必会，一定……会把 | |
③（表惊讶、遗憾的）竟然、居然 | |
④（与疑问词连用，表意外、惊讶、纳闷等的）究竟是，到底 | |
⑤（用于表示命令、建议、请求等词后面的that从句中，且should可以省略）应该，必须 |
①You should apologize to him.
②The photos should be ready by 12:00.
③I’m surprised that you should speak in such a way.
④Who should ccome in but my old friend Betty.我当究竟是谁进来了呢，原来是我的老朋友贝蒂呀。
⑤I suggested that he (should)change his mind.
My suggestion was that he (should)change his mind.
注意：ought to表示 “应该” (与should同义, 只是语气稍重一些), 也可表示推测。
You ought to take care of him.
He ought to be home by now.
8.will/would
①请求、建议，would比will委婉客气
Would you pass me the book?
②表示意志、愿望和决心
I will never do that again.
They asked us if we would do that again
③可表示过去反复发生的动作或某种倾向
During the vacation he would visit me every week
The wound would not heal.
④表示估计或猜想
It would be about ten when he left home.
What would she be doing there?
9.dare和need
①need作为情态动词只有一种形式，只用于否定句和疑问句。
②dare作为情态动词用时有两中形式：dare和dared两个词形。
除了可以用于否定句和疑问句外，还可以用于条件从句或表示怀疑的句子中。
If he dare come,I will kick him out.
I don’t know whether he dare say.
Note:He doesn’t dare(to)answer the question.
Does she dare(to)enter the dark room?
10.情态动词+have done的用法
①could+have done：本可以做而实际上未能做
You could have done better, but you didn’t try your best.
②cannot+have done：表示对过去行为的否定推测
He cannot have been to that town.
③can+主语+have done：表示对过去行为的怀疑或不肯定
Can he have got the book?
④might(may)+ have done：对过去发生的行为不太肯定的推测
He may not have finished the work.
If we had taken the other road, we might have arrived earlier.
(Mood:might>may,possibility:might
⑤must+have done：对过去发生的行为肯定的推测。其否定式为：cannot have done
You must have seen the film.
You cannot have seen the film.
⑥needn’t+have done：本来不必要做的而实际上又做了
You needn’t have watered the flowers,for it is going to rain.
注意：didn’t need to(have to)do :没有必要做而实际上也没有做
I didn’t need to clean the windows.My sister did it 2 hours ago.
⑦should(ought to)+ have done：本来应该做而实际上又没有做。
其否定形式表示某种行为不该发生却发生了。
You should have started earlier, but you didn’t.
She shouldn’t have taken away my measuring tape, for I wanted to use it.
注意：本结构还可以表“推测”的意思
He should have finished the work by now.
到现在他应该已经做完那项工作了。
11.其它情态动词
①have to
have to表示 “必须, 不得不”, 在这个意义上与must很接近, 但must表示的是说话人的主观看法, 而
have to表示的却是客观需要. have to比must有更多的形式。
The TV set is broken. I have to buy a new one.
The students will have to know how to use the computers.
注意：在回答must的问句时, 否定式常用need not(needn’t)或don’t have to表示 “不必”。而不用
must not, 因为must not表示 “不可以”。
②used to
表示过去的习惯动作或状态(现在已不复如此)
—Did you use to go there to see your brother? /Used you to go there to see your brother?
—Yes, I did(used to). /No , I didn’t (usedn’t).
注意：would也可表示过去反复发生的动作或某种倾向，但是不涉及到现在。
③had better
表示 “最好(做……)”
We had better go now.
其否定式为had better not
