1、情态动词（一）情态动词的定义:情态动词表示说话人对某一动作或状态的态度。（二）情态动词的特点1. 情态动词有一定的词义。2. 情态动词不能单独做谓语，它必须和其他动词的原形一起构成谓语。3. 情态动词没有人称，数的变化。（三）情态动词的结构和意义1.情态动词的基本句型n 肯定句： 主语+情态动词+动词原形+.n 否定句： 主语+情态动词+not+动词原形+.n 疑问句： 情态动词+主语+动词原形+.2. 情态动词的意义 must“必须” ； can/could“能，会” ； may/might “可以”； should“应该”； would“愿，要” ； have to“不得不” ； need
2、“需要”（四）情态动词的基本用法1.can (could主要指过去时间 ) 1） 表示人或物本身所具有的能力，意为“能，能够，会” : Two eyes can see more than one. / I can swim very well.2） 表示可能（理论上或是逻辑判断上） He cant (couldnt) have enough money for a new car. 3） 表示允许： Can I have a look at your new pen? He asked whether he could take the book out of the reading-roo
3、m. 4） 表示对现在动作或状态的猜测，主要用于否定句和疑问句中或感叹句中: He cant (couldnt) be over sixty. 他不可能超过六十岁。5） could表示比can更委婉客气的提出问题或陈述看法，指的是现在时间。 Can (Could) you lend me a hand?帮我一把好吗？2. may (might)1）表允许，询问或说明一件事可不可以做，might指过去时间；但在疑问句中might也可指现在时间，语气比may更委婉。 May (Might) I ask for a photo of your baby? 我可以要一张你宝宝的照片吗？ 在回答以may
4、引起的问句时，肯定回答是一般可仍用may,或Yes, please. / Certainly./Sure./Of course. ；否定回答根据说话人的语气由强到弱分别选用: must not(mustnt)（禁止）/ had better not（最好别）/ may not（不行）2) may表可能,但所表示的可能性不如can所表示的那样肯定。might可以指过去时间，也可以指现在时间，但语气更加不肯定。He may be at home. 他可能在家。They might be having a meeting, but Im not sure. 他们有可能在开会，不过我不肯定。3. mu
5、st（have to表示客观需要）1）表示 “必须”（主观看法）时，用于肯定句或疑问句；用于否定句时表示“禁止”。We must do everything step by step. 我们一切都必须循序渐进地做。You must get home before 9:00.2）表示揣测。意为“想必、准是、一定”等，只用于肯定句。He must be ill. He looks so pale. 他准是病了。他的脸色苍白。3)must的疑问句，肯定回答用must， 否定回答用neednt或dont have to。4. should1）表责任或义务，意为“应该”，用于各种人称。 You shou
6、ld be polite to your teachers. 你对老师应该有礼貌。2）表推测，意为“想必一定、照说应该、估计”等。The film should be very good as it is starring first-class actors. 这部新电影是一流演员主演的，估计拍得很好。5.will1）表意愿,用于各种人称。I will do anything for you. 我愿为你做任何事。2) will在疑问句中用于第二人称，表示询问对方的意愿或向对方提出请求Will you close the window? 请你把窗户关上好吗？6.would1）will的过去式，
7、表示过去时间的“意志、意愿”。 They would not let him in because he was poorly dressed. 他们不让他进去因为他衣着破旧。 I said I would do anything for you. 我说过我愿意为你做任何事。2）would用于现在时间，表示比较委婉地提出请求、建议或看法。 Would you like another glass of beer? 再来杯啤酒好吗？7.need1) need作为情态动词，主要用于否定句疑问句；作为实义动词可用于肯定句，否定句或疑问句中。You neednt telephone him now.
8、你现在不必打电话给他。2) 回答由need引起的问句时，肯定回答一般用must，否定回答是用neednt-Need I come?-Yes, you must.-我需要来吗？-需要。情态动词练习题(一) 单项选择1. _ I take it out? Im sorry, you _.A. Could .couldnt B. Might.might notC. Could.can D. May.can2. Need we do this job now?Yes, _.A. you need B. you should C. you must D. you can3. _ to have lunc
9、h with us today?A. Do you likes B. Would you like C. Will you liked D. Have you liked4. -Is John coming by train? -He should, but he _ not. He likes driving his car. A. must B. can C. need D. may5. Peter _ come with us tonight, but he isnt very sure yet.A. must B. can C. may D. will6. I thought you
10、_ be hungry, so I have brought you some cakes.A. may B. might C. can D. could7. Come on! We _ hurry because there isnt much time left.A. may B. must C. can D. need8. Amy did best in the English test. She _ hard last week.A. must working B. should have worked C. should work D. must work9.Would you li
11、ke to drink some juice? Thanks._,but I have drunk a lot if tea.A. Id love to B.I think so C.Im afraid not D. I dont think so.10.May I smoke here?No, you_! Look, there is a “NO SMOKING”sign here.A.may B.may not C.neednt D.mustnt11.Listen!Helen is singing in the next room. It_be Helen. She has gone to
12、 Beijing.A.cant B.mustnt C.may D.should12.What do drivers do when the traffic lights turn red? They_stop and wait till the green light.A.must B.can C.may D.need(二)根据语境用适当的情态动词填空：1.“_I leave school now?”“No, you_clean the classroom.”2.Its time for class. You_stop plalying football, or you_be late for school.3.“_they answer the queation in Russion?”“No, they_.”4._I hand in my paper now.No, you _.But you_hand it in tomorrow.5.“_you skate?”“No, I_.But my brother_”6.We_cross the street carefully.7.He is very clever. He_know the answer.3
