1、情态动词定义：表示说话人的语气和情态，没有人称和数的变化，不能独立做谓语，只能和动词原形一起构成谓语。掌握情态动词 can must may should need could 等的用法：1.must (1)必须 eg: You must finish your homework today.-Must I finish my homework today?肯定回答：Yes, you must. 否定回答：No, you neednt.(2）一定，肯定（ 表示肯定推测） eg:This book must be Lilys,it has her name on it. mustnt 不许，千万
2、别，禁止eg: You mustnt cross the road when the traffic light is red.2.can (1)能，会（表示具备某种能力） eg:I can swim.(2)允许，可以 eg:Can I sit here?cant (1)不能，不会 eg: I cant swim.(2)不可以，不允许 eg:You cant sit here,this seat is for my daughter.(3)不可能（表示否定推测）eg:That man cant be Mr.li,he has gone abroad.3.may (1)允许，可以 （此用法和 c
3、an 的第二种用法相同） eg:-May I come in? 肯定回答：Yes, you may. 否定回答： No, you cant/mustnt.(2)可能（表示不肯定推测） eg:That man may be Mr.Li, I hear he has come back.may not 可能不eg:That man may not be Mr.Li, I hear he hasnt come back.4.should 应该 eg: You should study hard.Shouldnt 不应该 eg: You shouldnt stay up late,its bad fo
4、r your health.5.need 需要（做情态动词时常用于一般疑问句和否定句）eg:(1)-Need I finish my homework today? 肯定回答：Yes, you must. 否定回答：No, you neednt.(2）You neednt finish your homework today.6.could (1)（过去）能，会 eg:I could swim when I was young.(2) 用于一般疑问句，表示委婉的请求 eg:Could you please open the window?7.might 可能（极其不肯定的推测） eg:This book might be Lilys , but Im not sure.
