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新课标人教版课件系列,高中英语 必修3-1.6,Grammar,情态动词用法,1) can的主要用法是： A. 表示体力或脑力的能力： eg. The girl can dance very well. B. 表示说话的推测事物的可能性等: eg. Can the news be true? C. 在口语中, can可以表示请求或允许: eg. Can I sit here?,can 和could：,2) could的主要用法是： A. could 是can的过去式, 表示与过去 有关的能力和推测: eg. We all knew that the young man couldnt be a doctor. B. could可以代替can表示请求, 但语气较can客气、委婉:,eg. Could you lend me your dictionary? Could I use your bike? 3) can和could接动词的完成形式，表示可能已经做某事。can用在否定和疑问句中, 表示不相信、怀疑等态度。 eg. They cant have gone out because the light is still on.,may 和might ： may 常用来表示： A. 表示请求、允许;比can较为正式: eg. May I come in ? You may go now. B. 表示说话人的猜测: “也许” “可能”: 通常只用于肯定句和否定句中。,eg. -I believe the man is from England. -But I may be wrong. The guest may arrive this afternoon. 在肯定句中，may 的可能性比can 高，may 表示现实的可能性，can 表示理论上的可能性。如：,The road may be blocked. 这条路可能不通了。 The road can be blocked. 这条路可能会是不通的。 在疑问句中，表示可能性用can。 如：Where can he be? 他会在哪呢？,C. 表示祝愿;但语气较正式: eg. May you succeed! May you have a good journey! might 的用法有: 多在间接引语中表示过去的可能和允许。如: She said that he might take her bike. 她说他可以拿她的自行车去用。,除了在间接引语中以外，might 一般不表示过去的可能或者许可。如要表示过去的可能可以用could, 表示过去的许可可以用was( were) allowed to 或者 had permission to 。 表示现在的可能，其可能性要比 may 小。如：,She might go home tomorrow. 说不定他明天会回家。 表示现在的许可, 语气比may 较委婉, 一般用于疑问句(包括间接疑问句), 不可用于肯定句或者否定句。 如: Might I have a word with you? 我可以和你说句话吗？,will和would：,1. will是助动词或是情态动词？ will用于构成将来时是助动词。用于表示“意志”“决心”“请求”是情态动词。would亦同理。 eg. I will tell you something important. 我要告诉你一些重要的事。 （助动词）,Will you tell her that Im here? 请您告诉她说我在这儿，好吗？ （情态动词） 2. 在疑问句中用于第二人称，提出请求或询问。 eg: If you want help - let me know, will you? 如果你需要帮助, 让我知道, 好吗?,Will you type this, please? 请打印这个，好吗？ Wont you sit down? 请坐下，好吗？ 3. would比will客气委婉。 eg: Would you help us, please? 请您帮助我们，好吗？,（表请求）,Id go there with you. 我要和你一块到那儿去。 Teacher wouldnt allow it. 老师不会允许这件事。,（表意愿）,（表许可）,shall和should：,1. shall用于构成将来时是助动词。 shall用于征求对方的意见，表示 “决心” 是情态动词。 eg: Perhaps I shall pay a visit to England this winter. 可能今年冬天我会去英国观光。 （构成一般将来时, 助动词）,Shall we go by train, Mom? 妈妈，我们乘火车去好吗？ （用于征求对方的意见，情态动词） I shall go at once. 我必须立即去。 （表 “决心”，情态动词）,2. should表示义务、建议、劝告，意为 “应该”。 “should+ have+过去分词” 表示本应该在过去做但没有做。 eg: You should keep your promise. 你应该遵守诺言。 She should have passed the exam. 她应该通过考试的。,must 的主要用法：,1. 表示必然性。 eg: We must all die. 人总要死的。 2. 表示强制或者义务。 eg: You must get up early. 你必须早起来。,注意: must not 的意思是不许可，不应该或者禁止。 如：We mustnt waste our time. - May I take this magazine out? - No, you mustnt. must 用于一般疑问句的时候，肯定回答应该用yes, please 或者 Im afraid so, 其否定回答应该用 neednt 或者 dont have to。如：,表示推测，语气非常肯定，近乎确定的意味，一般用在肯定句。 如：It must be eleven oclock now. He must be crazy. 在表示推测的否定或者疑问句中必须用 can, 不可以用 must。,If Mary didnt leave here until five oclock, she cant be home yet. 如果玛丽五点才离开这儿，他此时一定还未到家。,2. A: _ Xiao Feng find the origin of Easter from that book? B: No, he _.,1. A: _ you like to go to a special event with us on Saturday? B: Yes, I _ _.,Would,d like to go with you on,Saturday,Could,couldnt find it,Exercise,3. A: _ I go with my friend to the harvest festival? B: Yes, you _ _.,4. A: If I want to be a doctor _ I study science? B: Yes, you _.,should study science,May,may go ( with your,should,friends ),5. A: He is very handsome. _ he play the role of the prince? B: No, he _ _.,cant play the role of the,Can,prince,6. A: The neighbour s children are older this year. _ they stop playing tricks at Halloween? B: Perhaps, they _ _. _ _.,Might,or Should,might stop,or should stop playing tricks,playing tricks at Halloween,at Halloween,-_ I go out to play, mum? -No, you_. You should do your homework first. A. Might; wouldnt B. May; had better not C. Must; mustnt D. Need; mustnt,B,Practice,2. -Where is Emma? -I cant say for sure where she is, but she_ be out shopping. A. can B. should C. must D. may,D,3. The room is in a terrible mess; it _ cleaned. A. cant have been B. couldnt be C. may have been D. would be,A,4. How _ you say that you really understand the whole story if you have covered only part of the article? A. can B. must C. need D. may,A,5. There _ be any difficulty about passing the road test since you have practised a lot in the driving school. A. mustnt B. shant C. shouldnt D. neednt,C,
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