May-might--could表可能性用法.doc

May, might, can, could 表可能性 1)may/might 表示可能，往往可以交替使用，并无时间上的差异，只是用 might 在口气上比用 may 更加不甚肯定，从而比较婉转。may/might 既可表示现在的可能 ： e.g. It may/might be true. He may/might be still waiting at the door. 也可表将来的 可能 ： e.g. He may/might leave tomorrow. He may/might not to leave next week. 在疑问句中表示 可能 ，须用 can 而不用 may e.g. Where can he be? He may be in the office.2) 用 can /could 表示现在的可能，在口气上 could 比较婉转。 e.g. Thats not mine. Whose can it be ? It could be Johns. 用 can ，表示可能，较多的用于否定句中，而 could 则不受此限。 e.g. If you dont have a guide, you could lose your way. (=its possible for you to lose your way.) It cant/couldnt be true. The moon cannot always be at the full. can 与 may 的区别 在否定句中，用 can 表示可能与用 may 表示可能往往产 生含义上的微妙差异：用 can 表示可能往往表示逻辑上的 可能性；而用 may 表示可能则指事实上的可能性 。 e.g. The road can be blocked. (=Its possible for the road to be blocked.) The road may be blocked. (=Its possible that the road is blocked.)Another example: Mr. Reed is in poor health. He can be ill at any time. Mr. Reed looks pale. He may be ill.3)表示过去的可能，可用 may/might+ 不定式完成体或不定式完成进行体 ，在这里用 may/might ，也只有口气上婉转程度的差异，而没有时间上的区别 ：e.g. He may/might have been hurt. She may/might have missed the train. 也用 can/could+ 不定式完成体 表示过去的可能e.g. He cant/couldnt have been hurt. She cant/couldnt have missed the train. 用 might/could+ 不定式完成体 有时可以表示本来可能发生但没有发生的，或者本来可能完成却没有完成的动作。 e.g. You might have killed yourself. （你本来可能送命的。） You might have finished the work last week. summary 句型 情态动词 释义 例子 肯定句 May fml , might, 表示某事可能发生或称为现实 He may/might be still waiting at the door. could 人们常用以表示所说的话并不肯定 If you have a guide, you could lose your way. can 谈论事情一般的可能性而不是某件事在某个特定情况下发生的可能性 The temperature can sometimes reach 35 in July. 疑问句 Could( nt ), can be likely, might fml Could it be that you dont want to leave? 否定句 Cant, couldnt 表示某件事不可能是事实 There are plans to rebuild the town centre, but it cant/couldnt happen for another ten years. May not, might not 表示可能某件事不是事实 There are plans to rebuild the town centre, but it may not/might not happen for another ten years. 一、表示对过去情况的推测或估计may might have done 肯定句 可能大概（已经）否定句可能还没有can could have done 否定句 不可能（已经）疑问句 可能也许（已经）了吗？说明：1might could有时并不是may can的过去式，而是表示一种委婉的语气或更小的可能性。2might have done有时可用于疑问句中，此时might就相当于can could。比较may和might1、表示允许或请求；表示没有把握的推测；may 放在句首，表示祝愿。例如：May God bless you!愿上帝保佑你！He might be at home.他可能在家。注意：might 表示推测时，不表示时态，只是可能性比may 小。2、 成语：may/might as well，后面接不带to 的不定式，意为不妨。例如：If that is the case, we may as well try.如果情况确实如此，我们不妨试一试。典型例题Peter _come with us tonight, but he isnt very sure yet.A. mustB. may C. can D. will答案B. 表可能性只能用may。此句意可从后半句推出。Attention推测的否定形式，疑问形式用cant, couldnt表示。例如：Mike cant have found his car, for he came to work by bus this morning.迈克一定还没有找回他的车，因为早上他是坐公共汽车来上班的。注意：could, might表示推测时不表示时态，其推测的程度不如can, may。练习1、-Could I borrow your dictionary?-Yes, of course, you_.A. might B. willC. can D. should答案C. could表示委婉的语气，并不为时态。答语中of course，表示肯定的语气，允许某人做某事时，用can和 may来表达，不能用could或might。will 与you连用，用来提出要求或下命令。should与you 连用，用来提出劝告。2I thought you _ like something to read，so I have brought you some books（MET 1986）Amay Bmight Ccould Dmust由题意可知被猜测的时间是（过去）将来，没有客观事实根据，猜测语气要求最弱，所以正确选项是B。3Peter _ come with us tonight，but he isnt sure yet（MET 1993）Amust Bmay Ccan Dwill由题意可知被猜测的时间是将来，没有客观事实根据，猜测语气要求最弱，所以正确选项是B。4Mary _be in Paris，for I saw her in the town only a few minutes ago（MET 1994）Amustnt Bcant Cshouldnt Dmay not由题意可知被猜测的时间是现在，有客观事实根据I saw her in the town a few minutes ago，猜测语气要求最强，所以正确选项是B（cant是must的否定式）。5.There were already five people in the car but they managed to take me as wellIt _ a comfortable journey（NMET 1995）Acant be Bshouldnt be Cmustnt have been Dcouldnt have been由题意可知被猜测的时间是过去，有客观事实根据there were already five