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1、 情态动词【归纳】一、can和could表示能力。can表示现在的能力，could表示过去具有某种能力。如：My brother can speak four foreign languages.Sophia could read when she was four years old.注意：can表示“能够”时与be able to同义，但can只有过去式could，而be able to可用于各种时态。另外，could表示某人过去有某种能力，而was / were able to表示某人通过努力、克服困难做成某事，相当于managed to。如：She will not be able t
2、o visit the hospital tomorrow. Mike was an excellent tennis player when he was young. He could beat anybody. The fire spread through the building very quickly, but fortunately everybody was able to escape. 表示许可。could比can表示的说话语气更委婉。如：You can have a piece of cake after youve eaten your vegetables!Coul
3、d I have a drink of water, please? 表示可能性。此时could不是can的过去式，它表示推测的可能性比can小。如：Can he still be alive after all this time? If youre not careful, you could get into even worse trouble. 二、may和might表示许可或征求对方许可。如：You may / might use my bicycle so long as you return it before 12:00.I cant eat; may / might I h
4、ave a little brandy?表示可能性。might比may语气更不确定，表示的可能性更小。如：He may / might get here in time, but I cant be sure. 三、will和would表示意愿。will表示现在的意愿，有时可用于条件句中，would表示过去的意愿（would如表示现在的意愿，语气较委婉）。如：I will help her if she asks us to. Ask, if you will, who the owner is. My friend asked if I would go with him. 表示征求意见或提
5、出请求。will与would均可用于主语是第二人称的疑问句中，表示征求意见或提出请求，此时would并不表示过去，而表示委婉语气。如：Im cold. Will / Would you shut the window, please?Certainly.表示习惯和倾向性。will表示现在的习惯，would表示过去的习惯。如：She will listen to records, alone in her room, for hours. When Ann was a child, she would often ask some strange questions.四、shall和should
6、shall在疑问句中用于征求对方意见，主要用于第一人称，也可用于第三人称，意为“要不要，好吗”。如：Shall we go out and have a walk after dinner?Shall Tom go there with me tomorrow?shall还可用于主语是第二、三人称的陈述句中，表示决心、允诺、警告、命令、威胁、规定或义务等。如：You shall be punished if you break the rule.Tell her that she shall have the bike tomorrow.should表示义务或责任、建议或劝告、推断等。如：We
7、 should take good care of our children.You shouldnt leave a baby alone in the house.I wonder whats happened to Annie. She should be here by now.should还可以表示惊讶、失望、遗憾等情感，此时意为“竟会”。如：Its strange that Jane should be late. Shes usually on time.Im sorry that you should think so badly of me.五、must和cantmust可表
8、示“必须做某事”，还可表推测。must表示推测时用于肯定句中，意为“肯定，一定”。如：I must go to the bank to get some money.Where is Tran Nguyen from?I know thats a Vietnamese name. He must be from Vietnam.cant可表否定的推测和判断，意为“不可能”。如：Youve just had lunch. You cant be hungry. 【即学即练】 从括号内选择合适的内容完成下面对话。1.A:Its a national holiday tomorrow so ther
9、es no public transport. How are Jane and Sue going to get there?B:I dont know. Itll be difficult. They _ (might, must) take a taxi, but they _ (might not, could not) come.2.A:Why is John wearing sunglasses? Its not sunny.B:I guess he _ (may, must) have some problem with his eyes.3.A:Were visiting th
10、eForest Parktomorrow morning. _ (Would, Will) you like to join us?B:Id love to, but I _ (can not, could not) go out tomorrow. Were getting a new sofa and the store _ (may, must) be delivering it tomorrow.4.A:Who is that man leaving the library? It looks like Peter.B:It _ (may, shall) be his brother.
11、 They are so alike that people sometimes mistake them for one another.A:Are you sure? I really think it is Peter.B:It _ (must, cant) be Peter. Hes in hospital.5.A:What are you doing here? You _ (shall, should) be at the meeting downtown at this moment!B:Someone called and told me the meeting was cancelled.A:Oh, No! You _ (must, cant) have been fooled. Peter phoned just now and said everyone is at the meeting except you!B:What?!答案1. might；might not 2. may 3. Would；can not；may 4. may；cant 5. should；must
