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1、情态助动词的推测性用法,能做推测性用法的情态动词：共九个,按可能性的程度的高低这九个情态动词可分为三档 一，表“可能”： might / may/could / can 二，表“很有可能”: should/ ought to / would/will 三，表“最有可能”:must,2. 能做推测性用法的情态助动词的句法特征 A. 其后的不定式可以采取完成体形式You must have thought about that. B.其后的不定式可以采取进行体形式 He must be working late at the office. C.可以用于there-存在句 There must b
2、e some mistake. D.其后的不定式为一般形式时通常是静态动词。 He must be there. E.主语可以使表示无生命的名词词组。 It must be George.,3.说话人推测的事情所发生的时间要根据情态动词后的动词形式来定，可以是现在，过去，将来，一般动词是非完成体形式则表示现在或将来，动词是完成体形式则表示过去时间，但完成进行体有两种可能一是相当于现在完成进行体，一是相当于过去进行体 He must be there.：现在 Our team might win the race.：将来 He must be working late at the office
3、.：现在（进行） He must be calling tonight.：将来 He may have come last year.：过去 They cant have been waiting so long:表现在完成进行 He must have been dozing.：过去 “进行”,例1： -Are you coming to Jeffs party? -Im not sure. I _go to the concert instead. A. must B. would C. should D. might,析：选D。Im not sure.的语境表明把握性不大，当然我去参加音
4、乐演奏会的可能性就比较小了，故不用must应用might,例 2： -_the news be true? No, it_be true. A. Can, cant B. May, cant C. May, may not D. Must, mustnt,析： 选A。,重点一 Can-cant vs Must-mustnt,Can表示具有某种能力，表示推测意为“不可能/可能”，多用于否定句和疑问句中 eg. 1.Where can he have gone？他可能会去2.It cant be true.这不可能是真的。 哪儿呢？ must表“义务”或“强制”，表示主观的必要；表推测意为“一定”
5、,用在肯定句中。 mustnt：表“禁止”eg.1.We must clean the room.（表示我们认为房间太脏了。）2.He must be at home before supper.（他晚饭前一定在家。） 即表推测的must的否定形式是cant而不是mustnt,重点二 情态动词的完成式用法,（,例1：I told Sally how to get there,but perhaps I _for her.had to write it out must have written it out C. should have written it out D. ought to w
6、rite it out,选C。分析语境可知，口头上告知Sally如何去那里是不够的，所以我本应书面告知，却有没书面告知之，显得应使用should /ought to have written表示遗憾之情。,例2： I was really anxious about you, you_home without a word.A. mustnt leave B. shouldnt have left C. couldnt have left D. neednt leave,析: 选B。由语境可知，我真的为你担心，所以你不应该一句话不说就离开家，但实际上你确实这么做了，显然应填shouldnt/o
7、ught to have left，表示责备。,（一）should /ought to have done本来应做而未做，表达遗憾感情色彩should /ought not to have done本来不应做而做了，表达遗憾感情色彩,（二） may/might have done可能已做 must have done 一定已做 cant have done不可能已做,例1：-Where is my pen?- I _it.A. might lose B. wouldnt have lost C. should have lost D. must have lost,例2： The light
8、in his room is still on, so he _ to bed. A. mustnt have gone B. must have gone C. shouldnt have gone D. cant have gone,析：选D。由于他房间里的灯还亮着推测，他不可能已经上床睡觉了，应填cant have gone 。,（三）might/could have done指本来可能/能做而实际未做，表达遗憾的感情色彩,You might have killed yourself本可能送命 I could have reported you本可以告发你 I could have pa
9、ssed the exam, but I failed. You could at least have sent five cards.你本至少可以寄5张明信片的。,（四）neednt have done表过去本来不必做某事却做了,Eg1.You neednt have bought that house Eg2.I neednt have gone to the station 比较 I didnt need to go to the station因为没有必要不曾前往,情态动词的异化现象,有些情态用于疑问句进行回答时，出现了异化现象，此时回答在某 个角度不能继续使用该情态动词， 而改用别
10、的动词。,例1：-Must I start at once? No, you_. A. neednt B. mustnt C. cant D. wont,析：A。由语境可知该答句表示“不必”，而mustnt表示“不准、禁止”，不符合语境，显然应使用neednt表示“不必”，但肯定句回答继续用must。,例2：-Need I hand in my exercise book at once? Yes, you_. A. must B. need C. can D. will,析：选A。根据规定need用于一般疑问句作肯定回答应换成must,而作否定回答时，使用need的否定式neednt。,ex
11、ercise,There were already five people in the car but they managed to take me as well. It _ a comfortable journey. A.cant be B.shouldnt be C.mustnt have been D.couldnt have been D,用合适的情态动词填空,1.I mailed that letter a week ago. He_（receive） it.我一周前就发出了那封信, 想必他一定收到了。 must have received 2.I cant find my keys. I （ leave） them at the school yesterday. may / might have left 3.Jack （arrive） yet,otherwise he would have telephoned me.cant have arrived,情态动词其他重点内容,1.各个情态动词的含义 2.几组词的比较 Can vs be able to p283 Must vs have to p287 Would vs used to p300 Finish translation on p303,
