情态动词表推测课件.ppt

1、ModalVerbs,must, can, could, will, would, may, might, shall,should, need, dare, had better, ought to,情态动词 can, could, may,might,must表推测的用法：,情态动词中的can, could, may, might, must都表推测。其中must的可能性最大，can / could次之，may / might最小。具体用法如下：1. must的用法（1）表示推测时，意思是“一定是”，语气肯定，较有把握。其否定形式mustnt表示“不准，禁止” He must be Ame

2、rican. You mustnt drive so fast in the street. 回答带有must的问句时，否定回答常用neednt或dont have to，表示“不必”，而不用mustnt Must I come back before ten? Yes，you must.(No, you neednt),must表推测只能用于肯定句。 如表示“一定不、肯定不”的意思时，改为否定用cant, 如询问某种可能时，应用can。He must know my address. 他肯定知道我的地址。 He cant know my address. 他肯定不知道我的地址。Can he

3、know my address? 他知道我的地址吗？ That man must be Sarahs husband.-No, he_ be her husband. She is still single.A. cant B. mustnt C. may not D. ought to Tom graduated from college at a very young age.Oh, he _ have been a very smart boy then. A. couldB. shouldC. mightD. must,情态动词表示推测时，可以推测现在/正在发生的动作/过去的动作 对现

4、在或一般情况的推测，用“情态动词+ be”，“情态动词+be doing”或“情态动词+have done”。 He must have a car now. （现在） He must be doing his exercises in the classroom.（正在进行） He must have done his homework. I didnt hear the phone. I _ asleep. A. must beB. must have beenC. should beD. should have been,在反意疑问句中，当附属部分含有表示推测意义的情态动词时，疑问部分的

5、助动词应与非推测情况下的用法保持一致。 He must be a worker, isnt he? She must have a car,doesnt she? She cant be a teacher,is she?,2. can / could的用法（1）can意思“会、可能”表示推测用于否定句或疑问句。Cant“一定不”，could 还可以用于表示客气、委婉、礼貌的请求语气。 Could I use your dictionary?Yes, you can. He cant be at home. What_ it be?-It_ be a mail box, for it is m

6、oving. It_ be a car.A. can; cant; must B. can; can; mustC. can; mustnt; must D. must; mustnt; can,3. may和might的用法（1） may, might表示推测意思是“可能”“也许”与I am not sure连用He may / might be American.注：might不表示过去时态，只是语气上比may更委婉，表示的可能性更小。（2）may, might表推测时，可于否定句，“可能不、也许不”，但不用于疑问句。He may / might not be at home. 他也许不在

7、家。 1Excuse me. Is this the right way to the Summer Palace? Sorry, I am not sure. It _ be. A. mightB. willC. mustD. can 2You might just as well tell the manufacturer that male customers _ not like the design of the furniture. A. mustB. shallC. mayD. need,“情态动词+have done”用法 must have done 表示主观上对过去已经发生

8、的行为进行推测，意“一定做了事” He must have visited the White House in the United States. may/might have done表示对过去已发生行为的推测，“也许/或许已经“。一般用于肯定句或否定句中，不用疑问句。用might则语气更加不肯定。You may have learnt the news. canhave done cannot have done表示对过去发生的行为的怀疑和不肯定，通常用在否定句和疑问句中。 Where can she have gone?,could have done表示“可能已经”之意，还可以表示

9、过去能做而没做的事You could have done better, but you were too careless. might have done表示“本来可能，但实际上没有发生的事情”。He might have given him more help, thought he was busy. should/ought to have done表示本该做某事，而实际上未做；用于否定句时，则表示不该做的事反而做了。You shouldnt have done it so carelessly./You ought to have returned the book earlier

10、.neednt have done表示“没必要做而实际上也没有做某事”You neednt have watered the plants, for it is going to rain.,Choose the best answers :1. I thought you_ like something to read. So I have brought you some books. A. ought B. might C. would D. must3. Peter 2_come with us tonight, but he isnt very sure.A. must B. may C. can D. will 3. Look, someone is coming. Guess_ .-Jack. Hes always on time.A. who can it be B. who he mayC. who he can be D. who it can be,4. David, you _play with the valuable bottle, you_ b