mustcanmay表示推测的用法.ppt

must, can, may表示表示“推测推测”的用法的用法一、对现在的推测一、对现在的推测（一）肯定推测：（一）肯定推测：must be... must be... 一定是一定是......eg: eg: You must be hungry after a long walk. You must be hungry after a long walk. 他们一定正在等我们让我们快点他们一定正在等我们让我们快点eg: They must be waiting for us. Let’s hurry up. eg: They must be waiting for us. Let’s hurry up. （二）否定推测：（二）否定推测：can't be... can't be... 不可能是不可能是......eg: He wears glasses all the time, his eyesight can’t be good.eg: He wears glasses all the time, his eyesight can’t be good. 你不可能饿了，你刚刚吃过晚饭。

你不可能饿了，你刚刚吃过晚饭eg: You can’t be hungry, you have just had dinner. eg: You can’t be hungry, you have just had dinner. （三）不确定推测：（三）不确定推测：may be... may be... 可能可能( (不不) )是是......eg: eg: The news may be true, I'm not sure.The news may be true, I'm not sure. 她现在可能正在和她的同学们玩她现在可能正在和她的同学们玩eg: eg: At the moment she may be playing with her classmates.At the moment she may be playing with her classmates. 二、对过去的推测二、对过去的推测（一）肯定推测：（一）肯定推测：must have done... must have done... 一定做过一定做过......eg: You must have left your bag in the theatre. eg: You must have left your bag in the theatre. 昨天肯定下过雨了，地面是湿的。

昨天肯定下过雨了，地面是湿的eg: It must have rained last night, the ground is wet.eg: It must have rained last night, the ground is wet.（二）否定推测：（二）否定推测：can't have done... can't have done... 不可能做过不可能做过......eg: eg: He doesn't know that book at all, he can’t have read it very He doesn't know that book at all, he can’t have read it very carefully.carefully. 他不可能杀了人，因为他那时和我在一起他不可能杀了人，因为他那时和我在一起eg: He can't have killed the man, because he was with me at that eg: He can't have killed the man, because he was with me at that time.time.（三）不确定推测：（三）不确定推测：may have done... may have done... 可能做过可能做过......eg: He may have arrived at school. He is the early bird.eg: He may have arrived at school. He is the early bird. Anna Anna昨天可能见过昨天可能见过TomTom。

eg: eg: Anna may have seen Tom yesterday. Anna may have seen Tom yesterday. 从A、B、C、D四个选项中，选出最佳选项1. Jenny ___ with him at that time, for I was having dinner with her in my home. A. can’t have been B. mustn’t have been C. must have been D. may have been2. It is cold in the room. They ___ have turned off the heating. A. must B. ought to C. should D. could3. — Someone is knocking at the door. — It ______ be our neighbour. A. may B. can't C. must D. shouldAＡＡA4. I didn’t hear the phone. I ____ asleep. A. must be B. must have been C. should be D. should have been5. Johnson ____ be a policeman. He is much too short. A. may B. mustn’t C. should D. can’t6. — My friend ______ a thief. I believe her. A. can't have been B. can't be C. musn't be D. may be7. — Who told you the news? — I don’t remember clearly. It ___ Mary. — It ___ Mary. She doesn’t know it. A. may have been; can’t be B. can be; mustn’t be C. must have been; can’t have been D. may have been; may not beBBDA。