must,can,may表示“推测”的用法.ppt

1、must, can, may表示“推测”的用法,一、对现在的推测 （一）肯定推测：must be. 一定是. eg: You must be hungry after a long walk. 他们一定正在等我们。让我们快点。 eg: They must be waiting for us. Lets hurry up. （二）否定推测：cant be. 不可能是. eg: He wears glasses all the time, his eyesight cant be good. 你不可能饿了，你刚刚吃过晚饭。 eg: You cant be hungry, you have just

2、 had dinner. （三）不确定推测：may be. 可能(不)是. eg: The news may be true, Im not sure. 她现在可能正在和她的同学们玩。 eg: At the moment she may be playing with her classmates.,二、对过去的推测 （一）肯定推测：must have done. 一定做过. eg: You must have left your bag in the theatre. 昨天肯定下过雨了，地面是湿的。 eg: It must have rained last night, the ground

3、 is wet. （二）否定推测：cant have done. 不可能做过. eg: He doesnt know that book at all, he cant have read it very carefully. 他不可能杀了人，因为他那时和我在一起。 eg: He cant have killed the man, because he was with me at that time. （三）不确定推测：may have done. 可能做过. eg: He may have arrived at school. He is the early bird. Anna昨天可能见

4、过Tom。 eg: 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. cant have been B. mustnt 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

5、 C. should D. could 3. Someone is knocking at the door. It _ be our neighbour. A. may B. cant C. must D. should,A,A,4. I didnt 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. mustnt C. should D. cant 6. My friend _ a thief. I believe her. A. cant have been B. cant be C. musnt be D. may be 7. Who told you the news? I dont remember clearly. It _ Mary. It _ Mary. She doesnt know it. A. may have been; cant be B.