1、情态动词表示可能性的用法,一、情态动词表示对现在的推测 1.Johnny,you _ play with the knife, you _ hurt yourself. A.wont;cant B.mustnt;may C.shouldnt;must D.cant;shouldnt 2.Mary _ be in Paris,for I saw her in town only a few minutes ago. A.mustnt B.cant C.shouldnt D.may not1.B。mustnt表示“禁止，不可以“，may表示现在可能发生的事情。选项C中的must表示现在肯定会发生某
2、事，因此不符合语境。 2.B。cant意为“不可能“，同mustnt含义不同，不可混淆。,知识归纳 1.mustmust只能用于肯定句中，表示说话人自己相信某事现在是事实，可译为“肯定，一定“。若表示某事不是事实，要用cant(不可能)，不能用must not。例如： (1)Oh，you must be Marys husband.噢，你肯定是玛丽的丈夫。 (2)The two conflicting messages cannot possibly be true.这两条相互矛盾的消息不可能都是真的。,2.could,might,maycould, might, may可表示现在某事有可能发
3、生或可能是事实。may比could和might稍正式一些。 (1)Dont eat it. It could be poisonous.别吃，这东西可能有毒。 (2)His dictionary might be the same as yours.他的词典也许与你的一样。 (3)He may be at home now, for the light is on.他可能在家，因为灯亮着。注意：can在肯定句中，不能表示实际可能性，即不能表示某个特定事件可能会发生。can表示实际可能性一般用在疑问句和否定句中。例如：,(4)-Can it be your mother?-No，it cant
4、be her. It may be my father.-可能是你妈妈吗？-不,不可能是她。也许是我爸爸。 (5)It could well be that rich people treasure peace more highly than poor people.有钱人可能比穷人更加珍惜和平。3.might not，may not 可表示某事可能不是事实，而could not和cannot用来表示某事不可能真实。 (1)He might/may not be in England at all.他也许根本就不在英国。 (2)Kissinger cannot/couldnt know wh
5、at the situation is in the country.基辛格不可能知道这个国家的局势。,二、表示将来可能性 1.-Is John coming by train?-He should，but he _ not. He likes driving his car.A.must B.can C.need D.may2.-Are you coming to Jeffs party?-Im not sure. I _ go to the concert instead.A.must B.would C.should D.might 3.-When can I come for the
6、photos?I need them tomorrow afternoon.-They _ be ready by 12：00 oclock.A.can B.should C.might D.need,D. may表示对将来的推测，can对将来的推测，不用在肯定句。,D,B. should表示试探性的推断。might不符合此处的语境。,知识归纳 1.must,cannot,could,might,may其用法与前面提到的谈及现在可能出现的情况用法相同。might表示可能性较小，而may可能性较大。 2.should，ought to 可表示某个特定事件可能会发生，意思为“很可能“。 (1)Th
7、is course should be quite interesting for you.这门课程对你来说很可能十分有趣。 (2)-Ive bought thirty pints of beer.-That ought to be enough.“我已买了三十品脱的啤酒。“那应该是够了。“ 注意：should和ought to亦可用来谈及现在可能性很大的事情。 (3)That should be John coming upstairs now.那应该是约翰正在上楼。,三、表示过去可能性 1.-There were already five people in the car but the
8、y managed to take me as well.-It _ a comfortable journey.A. cant be B. shouldnt C. mustnt have been D. couldnt have been2.My sister met him at the Grand Theatre yesterday afternoon，so he _ your lecture.A. couldnt have attendedB. neednt have attendedC. mustnt have attendedD. shouldnt have attended,D,
9、A,知识归纳“情态动词have过去分词“可用来表示对过去发生某事的推测。 1.must have done 表示过去肯定发生某事，只用于肯定句中。在否定句和疑问句中 can/could-, can/could not have done，表示过去不可能发生某事。 (1)-The lights have gone out.-A fuse must have blown.“电灯灭了“。“一定是保险丝断了。“ (2)Where can/could John have put the matches? He cant/couldnt have thrown them away.约翰可能把火柴放到哪儿了
10、？他不可能扔掉了。,2.could/might/may have done 可表示过去某事有可能是事实，但这件事到底是不是事实，说话人并不知道。 (1)She could/may/might have gone off with some friends.她可能与一些朋友出去了。 (2)-Pollys very late.-She may have missed the train.“波莉晚了。“她也许误了火车。“ 3.might not/may not have done 可表示过去某事可能没有发生或可能不是事实。 (1)They might not have considered me as their friend.他们可能没有把我看作朋友。 (2)The couple may not have been ready for this pregnancy.夫妻俩也许没有为这次怀孕作好准备。,
