1、Unit 2 Lets celebrate！情态动词（2）1、情态动词的定义 情态动词（Modal verb），本身有一定的词义，表示语气的单词。但是情态动词不能独立作谓语，只能和动词原形一起构成谓语。情态动词用在行为动词前，表示说话人对这一动作或状态的看法或主观设想。情态动词的含义虽然数量不多，但用途广泛，英文中常见的有：can(could),may(might),must,need,ought to,dare(dared),shall(should),will(would)归纳：1）情态动词后接动词原形;2）没有人称和数的变化;3）不能单独作谓语,与后面的动词共同作谓语;4）其否定形式在后
2、面直接加not2、must1）表示必然性eg.We must all die.人总要死的。2）表示强制，义务eg.You must get up early.你必须早起来。注意：1）must not“禁止”如：We mustnt waste our time.-May I take this magazine out?-No,you mustnt.2）must 用于一般疑问句的时候，肯定回答yes,please 或者 Im afraid so,其否定回答用 neednt 或者 dont have to.3、will/would/used to eg.1)If you will read the
3、 book，I will lend it to you.2)Would you come into the bar and have a drink with me?3)Every evening he will have a walk along the river.4)I still remember my happy childhood when my mother would take me to Disneyland at weekends.5)He used to spend all his money on food and drink;now he lives simple l
4、ife.归纳用法1)will/would表示意愿,可用于各种人称。2)will/would表示“请求，建议”此时would比will更委婉。3)will/would表示习惯，意为“总是，习惯于”。与 used to相比,would表示过去重复、习惯性动作；而 used to则强调过去与现在的对比，过去常常，但现在可能已不复存在的动作。4、情态动词+have done1)Since nobody gave him any help,he must have done the research on his own.2)He cant have gone to Shanghai,for I saw
5、 him a minute ago.3)He might have said so at the meeting,but Im not sure.4)You could have done better,but you didnt try your best.5)I was really anxious about you.You shouldnt have left home without a word.6)You neednt have told him the news:he has heard it already.归纳用法*表示对过去的推测1)must have done表示对过去
6、发生的事情十分肯定的推测，意为“一定做过某事”2)can/could have done用于否定句和疑问句,表示对过去发生的行为的怀疑和不肯定，意为“不可能已经”或“可能已经了吗?”3)may/might have done用于肯定句和否定句表示对过去发生某事的可能性的推测，意为“或许做过某事”或“或许没做过某事”*表示后悔、责备或遗等情绪4)can/could have done用在肯定句中，表示对过去没有实现的可能性的遗憾，意为“本来能做实际上却未做”5)should/ought to have done表示本该做某事而实际上未做;否定式表示本不该做但却做了6)neednt have done表示做了本来不必做的事。疑问肯定否定Can/Could you do sth?Yes,I/we/can.No,I/wecant/couldntMay I do sth?Yes,you may/can.No,you musnt/may not.Must I/we do sth?Yes,you must.No you neednt/dont have toNeed I do sth?Yes,you must.No,you neednt/dont have to问句的回答方式 Class is over！Please finish your homework carefully.
