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1、,Grammar,Modal Verbs 情态动词,一、can和could的用法,表示能力. Tom can speak three languages. He could walk when he was one year old. 在表示能力,能够的时候can 和be able to的区别 A. can只有现在式和过去式(could), 而be able to则有更多的形式. B. 在表示能力时, “经过努力、设法做成某事“时,要用be able to,不可用can。,The fire spread through the hotel very quickly but everyone _
2、 get out. A. had to B. would C. could D. was able to,D,2. 表示客观可能性 That cant be Mary. Shes in hospital. There is someone outside. Who can it be? 3. 用于表示惊讶、疑惑或怀疑, 主要用于否定和疑问句中 Can he be serious? How can it be that ?,4.表示许可 (could可以代替can,表示语气较为婉转) Can/ Could I read your newspaper? You can take the car,
3、if you want. The boys could play football but the girls had to go to library.,5. 表示要求 Can you help me with this box? Can you feed the cat?,二. may和might的用法,1. 表示许可. 在表示请求允许时,might比may语气更委婉一些。用作此意时,它的否定形式可以用may not, might not,但表示“不可以”“禁止”“阻止”等意思时常用must not代替may not. May I go with my friends to the har
4、vest festival? -Yes, you may. -No, you mustnt. / No, you may not./ No, youd better not.,2. 表示可能性,有“或许”,“可能”的意思, 用might则语气更加不肯定。 He may/might be from Canada. They may/might have a lot of work to do.,三、must和have to的用法,1. have to和must含义相似,两者往往可以互换使用。但是有下列的不同。 A. must表示说话者命令或期待做成某事,have to用于他人发出指令或操纵的情况
5、。 The dinner must be ready at 6:00. I must go now. You have to pass a special exam to get into the school.,B. 两者的否定意思不同。Mustnt表示“禁止,不允许”。dont have to表示“不必”. You mustnt enter this room. You dont have to hand it in now. C. 两者的提问方式不同。 Must I start now? Do they have to finish the homework right now?,D.
6、must只有一种形式,have to有时态和人称的变化。 He has to come back to school at weekend. My mother had to work 12 hours a day. E. 询问对方意思时应用must Must I clean all the room? D.在间接指令中had to 取代must Mother said that the children had to be back by 4 oclock.,四、shall 和should的用法,1. 常用于第一人称的单数和复数(I , we) 2. 表示预言。 We shant know
7、the results until next week. This time next week I shall be sitting on a beach in Greece. I said I should be glad to help. 我说过我很愿意帮忙。 3.表示愿望和决心。 I shall write to you again at the end of the month. She was determined that we should finish on time.,4. 表示提供意见或建议。 Shall I wash the dishes now? Lets look
8、at it again, shall we? 5.表示命令和指示, 可用于第二、第三人称。 The students shall remain in their seats until all the papers have been collected.,五、will和would的用法,1. 可用于所有人称。 2. 表示对未来事物的预料。 Youll be in time if you hurry. 3. 表达对目前事物的预料。 Theyll be home by this time.他们现在一定是到家了。 4. 用于表示愿意或不愿意。 Ill check this letter for y
9、ou, if you want. Well not lend you any more money.,5. 用于表示请求。 Will you post this letter for me, please? Youll water the plants while Im away. wont you? 6. 用于发出命令或指示时。 You will carry out these instructions and report back this afternoon. 你要执行这些指示并于今日下午报告执行情况。 7.用于叙述真理时。 Oil will float on water.,1. wo
10、uld 是will的过去式, 可用于所有人称。 2. 用于提出请求时,would比will客气。 Would you pay me in cash? 3. 提出建议或邀请。 Would you like a cup of tea? 4. 用于叙述过去的习惯。 He would spend hours in the garden. 5. 句型:would like to do sth. 想要做,六、ought to 的用法,1. 表示责任或义务。 We ought to start at once. You ought to apologize to him. 2.表示劝告或推荐。 You ou
11、ght to improve your English before going to work in America. 3.作推测性结论。 If he started at nine, he ought to be here by now.,七、need 的用法,1. 表示必要。 If she wants anything, she need only ask. Nobody need be afraid of catching the disease. 谁都不用害怕能得这种病。 2. 当need是情态动词时没有人称的变化。 3. 否定形式:neednt do 疑问形式: Need I go
12、 at once? No, you neednt.,4.当是实义动词时。 A. 用法是need to do. I need to look up it in the dictionary. B. 有人称的变化。 He needs to hand in his report today. C. 否定形式:dont need to do 疑问形式:Do you need to go on a business trip to Wuhan?-No, I dont need to. Does she need to come ?- Yes, she needs.,八、表示推测的情态动词,1. can,
13、 could, may, might, must表示在一定时间(现在或过去)对发生和出现的事情进行推测、猜测、判断等 . 2. must表示对现在状态的肯定判断。 The light is still on in the room. He must be working there. 3. may/might 表示对现在情况的可能性推测。 He is not here today. He may be ill.,4. can用于否定句和疑问句,表示对于现在或当时情况的否定或疑问性的猜测。 There must be nobody. He cant be in the room. 5. Can
14、表示一般性的,理论上存在的可能,might而则表示正在发生或将要发生的具体可能性。 A wise man can sometimes make a mistake. I might go to Beijing by air next week.,表示猜测的确定性程度 must can (could) may might,九、情态动词+have done,情态动词+have done, 表示推测、后悔、遗憾、责备等语气。 may/might/must have done 表示对过去情况的推测或估计,表示“可能或肯定(已经)做了某事。 The ground is wet. It must have
15、 rained. 表示推测时,must have done 确定性最大,may have done 和might have done次之。,2. cant /couldnt have done表示对过去情况的否定性推测,表示“不可能已经做了某事”。 I cant / couldnt have lost the key. I never drop things. 3. Can/could在疑问句中表示对过去情况的疑问性推测,表示“可能已经了吗”?此时不能换为may或might. Someone must have broken into our bedroom. Who could have d
16、one it?,3. should/ ought to have done 表示过去该做某事而没有做的情况,表示说话人后悔、遗憾或责备的语气。 You are late. You should/ ought to have got up earlier. 你本应该早点起床。,4. Could have done表示对过去本来能够做却没有做某事的责备、惋惜、遗憾。 Oh, the train has left. You could have got up earlier. 噢,火车已经开了,你本来可以早点起床。,5. Neednt have done表示原本不必做某事却已经做了。 You neednt have apologized to her. It was not your fault. 你本不必向她道歉,那不是你的错。,十、走进高考,1.(10安徽32) Jack described his father,