高中情态动词课件大全

need /dare
a. need 表需要和必须常用于否定句和疑问 句,needn’t have done “本不必做…” b. dare 表敢,常用于否定句,疑问句和条件句 中。 c. dare与need 用做实意动词时有时态，人 称和数的变化,但dare用于否定句和疑问句时 常接不带to的不定式,need后要接带to的不定 式。
They may come here tomorrow. 他们可能还在等我们呢。 They may be still waiting for us.
2.might 可用于指过去的行为或者表示可能性 更小。
e.g.他也许在做功课吧。 He might be doing his homework now. 我问他我是否可以离开。
must 和have to
1.must用于一般问句中,肯定回答用must否 定式用 needn’t或don’t have to，做 “不 必”,mustn’t表示“禁止，不允许”
e.g.— Must I finish all assignments at a time? —Yes, you must. No, you needn't. You mustn’t get off while the car is still moving.
I asked him ―May I leave now?‖ I asked him if I might leave.
3.might/may have done,表示对过去发生的动 作进行可能性推测。 e.g.他可能去医务室了。 He may have gone to the clinic. 他可能已经从报纸上知道这个消息了。 He might have read about the news in the newspaper.
must
1.must 表示推测时， 只能用于肯定句。 e.g.这个电脑肯定出了问题。 There must be something wrong with the computer. 你努力学了一整天， 一定累了吧 You have worked hard all day. You must be tired.
may 1. I don't know where she is, she _______ be in Wuhan. must be marking 2. At this moment, our teacher ________________ our exam papers. 这时，我们老师想必在批改试卷。 3. The road is wet. It ________________ last night. must have rained
Grammar
modal verbs
can could may might shall should must will would 情态动词 ought to have to dare (daren’t) need (needn’t) used to
表示推测
不表示推测
情态动词有一定的意义，但没有人称和数的 变化，不能独立使用，它和后面的动词构成 谓语．
must , can/could, may/might 的用法
注意：must用于肯定句中可表示“偏偏”。 Naturally, after I told her what to do, my daughter must go and do the opposite. 自然地，在我交代女儿做什么之后，她偏偏要
3.must +have done 表示对过去发生的事情作 出的肯定判断 e.g.他们在玩篮球， 他们一定完成了作业。 They are playing basketball, they must have finished their homework. 路是湿的。昨天晚上一定下雨了。 The road is wet. It must have rained last night.
可能性依次减弱
(对过去情况推测：must may, might)+完 成时。 e.g. You must have met him before.
must—may—might可能性依次减弱
must只能用于肯定句，译成“一定”。否定 和疑问分别用can’t / couldn’t和can / could。
对现在或将来情况推测：must +动词原形。
must只能用于肯定。否定和疑问分别用can’t 和can。 e.g. He must tell a lie.
Can he tell a lie ? He can’t tell a lie.
*must-should/ought to –may-might/could+do
e.g. Could /Can it have happened last night ?
It couldn’t/can’t have happened last night.
can/could
1. can /could 表示推测时，只能用在否定句 或疑问句中。 e.g. It’s so late. Can Tom be reading? Can it be Mr. Green? 这个人不可能是玛丽， 她生病了。 It can’t be Mary. She has fallen ill. 她不可能在说谎。 She couldn’t be telling lies.
shall/should
1.shall 用于第二、三人称陈述句中，表示说话 人给对方的命令，警告，允诺或威胁。 e.g.1)You shall go with me.(命令) 2)You shall have the book when I finish it.(允诺) 3)He shall be punished.(威胁) 2. shall用于第一、三人称疑问句中，表示说话人 征求对方的意见和向对方请示。 e.g.4)Shall we begin our class?（征求意见） 5)When shall Mike be able to leave hospital?(请示)
must
可能的推测
+ V. + have done + be doing
may, might
否定的推测
+ V. + have done + be doing 可以用not表示“可能不” + V. + be doing + V. + be doing + have done
can’t, couldn’t
I wonder if you could help me. (请
求)
2. can/could have done 对过去发生行为的可 能性进行推测: 刚才我还看见他了， 所以他不可能出国的。 I saw him just now so he couldn’t have gone abroad. 门是锁着的， 所以她不可能在家。 The door was locked. She couldn’t have been at home.
2.表示“必须”这个意思时，must 和 have to 稍有区别。must着重说明主观看 法，have to 强调客观需要。另外， have to 能用于更多时态。 e.g. I don’t like this TV set. We must buy a new one. There was no more bus. They had to walk home.
做相反的事情.
2.must +be doing/do 表示对现在的动作进行 肯定推测 e.g.他现在一定在看小说. He must be reading novels now. 他们买了一辆新车。 他们一定很有钱. They have bought a new car. They must have a lot of money.
2. should 的用法 注意：should可表示“居然，竟然”。 e.g.我不敢相信这样一个绅士居然对老人如此 无礼。 I can’t believe such a gentleman should be so rude to the old.
3. should常表示劝告、建议、命令，与 ought to意义相近，但ought to多表示责任、 义务，语气强烈。在疑问句中通常用should 代替ought to。 e.g. Young people should learn how to use computers. Every citizen ought to obey law.
只作情态动词的
can/could, may/might, ought to， must 可情态可实义的 need, dare/dared 可情态可助动词的 shall/should, will/would 相当于情态动词的 have to, used to
must , can/could, may/might 的用法
You ought not to go.
4.should/ought to have done表示责备或 批评,意为“本应该做到…但没有做到…”,用 于否定则表示“本不该…但”ought to的语 气更强烈. e.g. You should/ought to have told her the truth earlier. She shouldn’t have left without saying a word.
3.用于条约，规定，规章等文件中，表示 一种义务，多用于第三人称中。 6) “The interest ___be divided into five parts, according to the agreement made by both sides.” declared the judge. A. may B. should C. must D. shall