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1、情态动词复习,1. must,1) 表示必须、必要。是说话人的主观看法 You must come in time. 在回答引出的问句时，如果是否定的， 不能用mustnt（禁止，不准），而用neednt, dont have to（不必）. - Must we hand in our exercise books today? - Yes, you must. - No, you dont have to / you neednt.,1. must,2) 表示推测、可能性（只用于肯定的陈述句） 1 Youre Toms good friend, so you must know what h
2、e likes best. 2 Your mother must be waiting for you now.,2、Might and may,表示请求和允许。might比 may语气更委婉，而不是过去式 否定回答时可用cant 或mustnt，表示“不可以，禁止”。 -Might/ May I smoke in this room? - No, you mustnt. - May/Might I take this book out of the room? - Yes, you can. (No, you cant / mustnt. ) 用May I.？征徇对方许可时比较正式和客气，而
3、用Can I.？在口语中更常见。,2）用于祈使句，表示祝愿。,May you succeed!,3) 表示推测、可能性（不用于疑问句）。,might不是过去式，它所表示的可能性比may小。 1He may /might be very busy now. 2Your mother may /might not know the truth.,三、can, could,1) 表示能力（体力、知识、技能）。 Can you lift this heavy box?（体力） Mary can speak three languages.（知识） Can you skate?（技能）,此时可用be a
4、ble to代替。Can只有一般现在时和一般过去式；而be able to则有更多的时态。 Ill not be able to come this afternoon. 当表示“经过努力才得以做成功某事”时应用be able to，不能用Can。如： He was able to go to the party yesterday evening in spite of the heavy rain.,2) 表示请求和允许。,-Can I go now? - Yes, you can. / No, you cant. 此时可与may互换。在疑问句中还可用could, might代替，不是过去
5、式，只是语气更委婉，不能用于肯定句和答语中。 - Could I come to see you tomorrow? - Yes, you can. ( No, Im afraid not. ),3) 表推测可能性。,肯定句中：can表示理论上的可能性；may表示事实上的可能性，如： In Yuyao, sometimes it can be really cold. Tom may go camping with us tomorrow, but he is not sure. 否定句和疑问句中，只能用can表猜测可能性。 Someone is knocking at the door, a
6、nd who can it be? It cant be Tom because he has gone to Beijing.,四、 shall,shall 用于第一人称，征求对方的意见。 What shall we do this evening? shall I clean the room for you?,2) shall 用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。 1. You shall fail if you dont work hard.(警告) 2. He shall have the book when I finish it.(允诺) 3. He sh
7、all be punished.(威胁),五. should,表示“应该”，常用来表示劝告、建议；认为“某人应该做某事”或“有义务责任做某事”。 We should obey traffic laws. You shouldnt watch TV every day。 You shouldnt have made this kind of silly mistakes. Tom should have brought his report today. 这时它可以和 ought to， be supposed to 互换使用,2) Should (ought to)表示推测时，是指有一定根据的
8、推测，意为“可能、该”,-When can I come for the photos? I need them tomorrow, -They _ be ready by 12:00,3. 表示惊讶的语气,You can never imagine such a gentleman should be so rude to a lady.,六： will 和would,1)表示意志或意愿：决心，愿意， We will do our best to save the child. 我们会尽力抢救这个孩子。 I told her to stop crying, but she just woul
9、dnt listen. 我叫她别哭,可她就是不愿听。,2)表示请求、建议或征求对方意见时，用Would you? 比用Will you?更婉转。如：,Will/Would you please keep the door open?请让门开着好吗？ Will/Would you go with me?你愿意和我一起去吗?,相关情态动词,would like表示愿意 I would like to have a word with you. 我想同你说句话。 would ratherthan宁愿也不愿 I would rather fail than cheat in the examinati
10、on. 我宁愿考不及格，也不愿意考试作弊。,七、need,1need作情态动词无人称或数的变化， 后接动词原形，多用于否定句和疑问句中。 如：You neednt worry.你不必担心 I neednt have brought the raincoat with me in such a sunny day yesterday.,2由need引出的一般疑问句，肯定回答常用must或have to;否定答语常用neednt. 如：,Need I answer the question? 我需要回答那个问题吗？ Yes, you must. -Yes, you have to.是的，你必须回答
11、。 -No, you neednt./you dont have to不，不必了。,由must引出的一般疑问句，肯定回答用must,否定答语用neednt或dont have to。如：,Must I do the work now? 我必须现在干这个活吗？ Yes, you must /have to. -No, you neednt /dont have to.,Need 做行为动词,Need sth Need to do sth Need doing=need to be done表被动 否定： dont need,八：dare 敢,通常用于疑问句、否定句或条件句中 Dare you a
12、sk him?你敢问他吗？ She dare not go out alone. 她不敢单独出去。 I dont know whether he dare try. 我不知道他敢不敢试。,注意：,1.有过去式dared。如： No one dared speak of it. 没有人敢提及此事。 2. How dare you/he/she/they?表示说话人对某人的行为表示愤慨。如： How dare you ask me such a question?你怎敢问我这样的问题? 3. I dare say表示“我相信，我认为，可能”。如： I dare say you are right.
13、 我认为你是对的,作行为动词：可用于各种句子中；在疑问句或否定句中，to经常被省略。如,Did anyone dare (to) admit it?有人敢于承认吗? He did not dare (to) leave his car there. 他不敢把车停放在那里。 If he dares to show up at her house Ill be surprised. 如果他敢出现在她的房子里，我会感到吃惊。,注意点一：,表推测可能性：must, can, may, might, cant, couldnt -I heard they went skiing in the mount
14、ains last winter. - it _ true because there was little snow where.,二、表推测的用法,1. must have done过去肯定做了某事 Since the road is wet, it must have rained last night. 不存在 mustnt have done 的形式。其否定或疑问形式须用 can(could) 来表示. 例如： He cant have missed the way. I drew him a map. “The dictionary has disappeared. Who cou
15、ld have taken it?”,may / might have done,I cant find my keys. I may / might have left them at the school yesterday. 我找不到我的钥匙了。我可能昨天把他们落在学校了。 John may/might not have passed the exam; he looks very sad.约翰可能没有通过考试。他看起来很忧伤。,3.can/could have done 表推测一般用在否定句和疑问句中，表示不相信或怀疑的态度。,Can/Could he have passed the exam?他可能通过了考试吗？ I think that he couldnt/cant have gone abroad. I saw him just now.我认为他不可能出国了。我刚才还看见他了。,
