情态动词讲解模版课件.ppt

情态动词讲解 can 1.表“能力“，could 表过去的能力 I can lift the stone. I can speak English while he cant. Who can play the violin? He got up early yesterday so that he could catch the early bus. 注： can 与be able to表能力时的区别：① 形式上；can有两种形式can 与could，而be able to有更多的形式。is(are)able to, was able to ,, has been able , will be able to , would be able to 等。be able to 只表能力而can 还可表可能性，惊异,许可等。② could与was able to表过去能力的差别：均表过去的能力，但was（were）able to还可表业已成功的行为（即：动作确实做了）。 2．表许可“ You can go now. You can use my dictionary. You can have a rest. -Can I smoke here?-No, you cant. 注：用could代替can在疑问句中，语气客气委婉，但在时间上还指现在. Could you lend me your bike? Could you tell me how to get to the station? 注：回答由could引起的问句，仍用can 而不用could。 -Could you wait a few more minutes?-Yes, I can. 3.表猜测“可能”，一般用于疑问句和否定句 -Can the news be true? -It cant be true. Where can he be? 注： (1)can‘t表“不可能”，语气断然否定。 (2) could在宾语从句中表过去的可能性，其它情况一般还表示现在的可能性只是语气比can委婉和更加不肯定。 I thought he could come . (3) can 亦可用于肯定句表可能，但表示的是逻辑推理上的可能性（或理论上的），非主观臆断。 There can be no noise on the moon because of sound being carried by the air . (4) can(could)…have done或can(could)…have been(done)用于疑问句或疑问句表对过去时或完成时的揣测。What can have happened to him ? He can not have read the book. He cant have been to Beijing. 4.表惊异惊讶“ How can you be so impolite? How can you say that? may may表“允许”“许可”“允诺”（征询对方许可）。 You may go now . May I use your bike? You may keep the book for 2 weeks . 注意： (1)其否定形式may not表示不可以，但更常用must not来代替may not表示不可以，禁止。 -May I watch TV after supper?-Yes, you may.(No, you mustnt .或No, you may not.或No, youd better not.) (2)与can的比较：may比can更正式。May I know your name? May I (he, we…)….?×May you….? (May you have a good journey! 此处表祝愿) (3).might代替may用于疑问句，更客气礼貌些，回答时仍用may。 -Might I use your telephone? -Yes, you may . (4)might not 不表示不允许 2．表“可能”. （1）用于肯定句和否定句（因为May I…?表征询许可）。The news may be true . He may not be at home now. I think he may come today(tomorrow).However fast you may run, you cant catch