情态动词1.表示推测情态动词在表示推测时的用法 一般情况正在进行的状况已经发生的事情过去一直在-must肯定（只用于肯定句） do be doing have donehave been doingcan/could(not)可能吗？不可能（只用于疑问句，否定句） do be doing have donehave been doingmay/might/could可能 do be doing have donehave been doingmay/mighr not可能不dobe doinghave donehave been doing例句a. -Hi, Tom .Any idea where Jane is?-She must be in the classroom. I saw her there just now.你好，汤姆。你知道琼在哪儿吗？她肯定在教室。我刚刚在那儿见到她的。b. -“Can he be at home?-No,he cant.他会在家吗？不可能。c. -Li Ping must be reading in the classroom.-No,he cant.I saw him in the hall just now.李平肯定正在教室看书。不可能。我刚刚看见他在大厅。注意比较： She may/might /could be at home.她可能在家。 She may/might not be at home.她可能不在家。 She cant be at home.她不可能在家。 She must be at home.她肯定在家。 Can she be at home?她可能在家吗？（注意以上几个句子的意思区别）d,She said that someone must have heard us in the toilet.她说肯定有人在厕所听到我们说话了。He might have done something wrong yesterday.他昨天可能做错事了。From 7to8yesterday evening,he must have been waiting for you.昨天晚上7点到8点他肯定一直在等你。注意：1)should有时也可表示推测意为“应该”例句：-When will I come for the phones?I need them tomorrow afternoon. -They should be ready by 12:00.我什么时候来取照片？我明天下午需要。12点以前应该没问题.注意2）Children mustnt play in the street.孩子们不能在街上玩。（mustnt不表示推测，表示不能，不允许）Mother is sleeping.You mustnt make any noise.妈妈在睡觉。你不能吵。2.should (not)have done本该-/本不该-（有谴责之意）ought(not) to have done本该-/本不该-You are late again. You should/ought to have started earlier.你又迟到了。你本该早点出发的。Why tell her the bad news ?You shouldnt/ought not to have let her know it.为什么把这个坏消息告诉她？你本不该让她知道的。注意：neednt have done本不需要-（无谴责之意）You neednt have so hurried.There is plenty of time left.你本不需要这么急忙。时间足够。3（1）-Must I stay ( at) home? -Yes, you must./No,you neednt./No, you dont have to.我一定要呆在家里吗？是的。/不，你不必了。（2）-May I go out now?-Yes, you may./No,you mustnt.我可以现在出去吗？是的，你可以出去。/不，你不能出去。（3）-Need I stay here?-Yes, you must.No,you neednt./No, you dont have to.4.Shall I /we /he/she/they do-?(在疑问句中用于第一，三人称)表示征求对方意见Shall I open the door?要我开门吗？Shall he stay for the night?让他留下过夜吗？You/He/They shall do-.(用于二，三人称肯定句中，表示允诺，强制，命令，警告等。If you insist on doing so ,you shall be punished.如果你坚持这么做，你就会受到惩罚。（警告）5.can,be able to表示过去某个时间经过努力能-，（只有一次）一般不用couldLast night ,they wre able to escape from the big fire.昨天晚上，他们从大火中逃出来了。6. Would/Could you do-?回答是应用can/will而不用would/could-Would you like to go with me? -Yes, I will. 情态动词练习一基本题1. In fact, you _ go outside at all. Theres a supermarket just downstairs.A. couldntB. mustntC. needntD. shouldnt2. -Did Mary come to the party? -I dont know. She _while I was out. A. may have come B. must have come C. might come D. could come3. Alice looks sad. Did you tell her about the accident? Yes, but I her just before her final examinations.A. should have told B. shouldnt have told C. neednt have told D. must have told4. “I know she was in because I heard her radio, but she didnt open the door.” “She _ the bell.” A. may not be hearing B. may not have heard C. must not have heard D. must not be hearing 5. - Look, Tom has fallen asleep. - Oh, he _ too late yesterday evening.A. might stay up B. should have stayed up C. could stay up D. must have stayed up6. We would join them for dinner_. A. should they ask B. shall they ask C.if they ask D.whether they ask7. _ it be true that the road is being blocked at this moment, for cars are moving like snails inch by inch A. may B. should C. can D. must8. As it turned out to be a small house party, we _so formally. A. neednt dress up B. did not have dressed up C. did not need dress up D. neednt have dressed up9. According to the school rules, no student_ go out of the school after eleven oclock at night without the teachers permission. A. will B.shall C. must D. should10. As we all know, he has regretted wasting the precious time when he_ studied hard playing computer games at school.Ashould haveBwould haveCmight haveDmust have11-May I stop my car here? -No, you_.A. cant B. mustnt C. neednt D. dont have to12. Must we clean the house now? No, you _.A. neednt B. may not C. mustnt D. cant13. John_his father about his failure in the exam.A. dares not tell B. dares not telling C. dare not tell D. dares not to tell14. You_ return the book now. You can keep it next week if you like.A. cant B. mustnt C. neednt D. may not15. Johnny, you_ play with the knife, you _hurt yourself.A. wont.cant B. mustnt.may C.