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1、九年级英语unit 8 语法（情态动词）情态动词：情态动词有具体的词义；情态动词没有人称和数的变化；情态动词后必须加上动词原形；情态动词同助动词一样，需要与其他词语一起构成句子的谓语。can ：1、表示能力，意为 “能 会”；2、表示请求， 允许， 意为“可以”；3、表示推测， 意为 “可能”。could：1、can 的过去式，意为“能、会”， 表示过去的能力2、在疑问句中表示委婉请求may：1、表示请求、许可，意为“可以” 2、表示推测，常用于肯定句中，意为“可能、也许”might：1、may的过去式 2、表示推测，常用于肯定句中，意为“ 可能、也许 ”must：1、表示主观看法，意为“必须
2、、应该”2、表示有把握的推测，用语肯定句need：1、表示需要、必须，主要用于否定句和疑问句中should：1、意为“ 应该”， 表示要求和命令 2、表示劝告、建议had better：意为 “最好”，表示建议（一） can 的用法1.表示能力（体力、知识、技能）。Can you lift this heavy box? Mary can speak three languages. Can you skate? Can只有一般现在时和一般过去式；而be able to可以用于任何时态时态。 Ill not be able to come this afternoon. 当表示“经过努力才得以
3、做成功某事”时应用be able to，不能用Can。 He was able to go to the party yesterday evening in spite of the heavy rain. 2.表示请求和允许, 此时可与may互换。在疑问句中还可用could, might代替，不是过去式，只是语气更委婉。(1).-Can I go now? - Yes, you can. / No, you cant. (2).- Could I come to see you tomorrow? - Yes, you can. ( No, Im afraid not. ) 3.表推测可能
4、性。Someone is knocking at the door, and who can it be?It cant be Tom because he has gone to Beijing.（二）、could的用法1、can的过去式， 意为“ 能、 会” ， 表示过去的能力。 He could write poems when he was 10.2、 could 在疑问句中， 表示委婉的语气， 此时 could 没有过去式的意思。-Could I use your pen? -Yes, you can. （三）、 may的用法1、表示请求、许可， 比can 正式。May I borr
5、ow your bike?You may go home now. 2、 表示推测，谈论可能性，意为“ 可能， 或许”。 It may rain tomorrow . She may be at home.3、 may的过去式为might ，表示推测时。可能性低于may。He is away from school. He might be sick.（四）、 must的用法1、must 表示主观看法，意为“必须、一定”。You must stay here until I come back.Must I hand in my homework right now?2、must否定形式mus
6、tnt 表示“ 一定不要 、千万别、禁止, 不许”。 You mustnt play with fire. Y ou mustnt be late.3、以must开头的一般疑问句，肯定回答用must，否定回答用neednt 或 dont have to 。-Must I finish my homework? -No, you neednt.4、must 一定，表示有把握的推测，用于肯定句中。The light is on, so he must be at home now.（五）、need的用法1、need 作情态动词时，情态动词+V原（以need开头的一般疑问句，肯定回答用must，否定
7、回答用neednt 或 dont have to 。-Need I stay here any longer? -Yes, you must. -No. you neednt . 2、need作实义动词时，有人称、数和时态的变化。当主语是人时用need to do sth,当主语是物时用need doing sth.I need to do it right now.He needs to learn more about the girl. （六）、dare 的用法(敢、敢于)1、dare 作为情态动词，无第三人称单数形式，只有一般现在时和一般过去时。Dare he tell them wh
8、at he knows?2、dare 作为实义动词(dare to do sth)，此时有人称、数及时态的变化。He doesnt dare to break his promise.（七）、should的用法1、should 意为“应该” ， 可表示劝告、建议、义务、责任等。We should protect the environment. 2、Should have done 表示对过去动作的责备、批评。You should have finished your homework.（八）、had better 的用法(最好，没有人称的变化)had better (not)do sthWe
9、 had better go now. You had better not give the book to him.表示推测含义的情态动词：must 一定can可能could可能may可能might可能may not可能不cant不可能1.- go to the cinema, mum? -Certainly, but you _ be back by 11 oclock.A. can B. may C. must D. need2.You _ get there by bus.A. dont need B. neednt to C. dont need to D. need dont t
10、o3.You _ worry about me. Its nothing serious.A. cant B. mustnt C. neednt D. wont4. The man in the office be Mr. Black because he went home just now.A.mustnt B.may not C.cant D.neednt5.-Can you go surfing with us this afternoon?-Id like to , but I look after my sister at home , because my mother is i
11、ll.A.need B.must C.have to D.should6.-May I take this book out of the reading room?- .Pease read it here.A. Certainly B.No, you neednt C.No, you mustnt D.No, you may not7.- Where is Mary? - She in the library. A.should be B.must be C.can be D.must have been8.His room is dark. He must to bed. A.go B.
12、be going C.have gone D.have been gone9.-Will your father stay home tonight? -Im not sure, He to work. A.must go B.can go C.may be gone D.may be going10.-Where is Tom? -He isnt here I think he have gone home. A.may B.must C.might D.A or B or C11 .-I think Helen is at home.-No, she be at home, for she
13、 phoned me from the airport just five minutes ago. A.mustnt B.neednt C.cant D.darent12. Hes late. What have happened to him? A.can B.may C.should D.must13.- he be watching TV now? -Yes, he be watching TV now. -No, he _ be watching TV now.”A. Must; can; mustnt B. Can; must; cant C. Must; must; cant D. Can; can; mustnt14. You must be a writer, you?A.mustnt B.are C.must D.arent15. You must have seen her yesterday, you?A.mustnt B.havent C.didnt D.dont16. You must have seen her, you?A.havent B.didnt C.dont D.A or B17.He
