情态动词专项复习.ppt

情态动词专项复习 What is the modal verb? 情态动词本身有一定的词义，表示说话人对某一动作的看法和态度，但不能单独作谓语，必须和另一个动词原形一起构成谓语.即所有的情态动词后面都接动词原形. Eg: I can swim . （否定句） I can’t swim. He has to go now . （否定句） He doesn’t have to go now. 常见的情态动词有: can , could , may ,might ,must , have to , should, ought to , had better, need等. 1.can和could都可以表示能力。Could是can的 过去式。 2.can和could表示请求允许。could不是can的过去式，是一种委婉的说法.。 3.表示猜测，可能性。can 通常用于否定句和疑问 句， can’t 意为“不可能”。 It can’t be true. 那不可能是真的。 Can /could的用法 1.---Amy, I hear you’ve got many foreign coins. __________ I have a look? --- Of course. Should B. Must C. May D. Need 2. Bill_________ be ill at home. I’m not sure. A. could B. can C. must D. may may的用法： 1.表示请求和允许 。 2.表示推测、可能性。may 则通常用于肯定句和否定句。 may not 意为“可能不”。 It may not be true. 那可能不是真的。 C D 用must, have to ,mustn’t 填空： 1.We __________ protect our environment. 2.You ________ play on the road. It’s dangerous. 3.My mother is ill, so I ___________ go now. 4.After such a long way, you ___________ be tired. 5.There was no bus. I _____________ walk home last night. must 侧重于表示说话人的主观看法，意思是“应该，必须”， 其否定式mustn’t意为“不应该，不准”。 must表示推测，意思为：一定，必定(只用于肯定句中) 。 have to侧重于强调客观条件需要做的事情。 have to 有人称、时态和数的变化。 must mustn’t have to must had to 用恰当的情态动词填空： You ___________ (must, should) bring a jacket to the cinema because you might feel cold. You ________ (must , ought to) go to the toilet before the film begins. You __________ (had better, have to) buy some popcorn or soft drinks before the film begins. You ____________(had better not, mustn’t) drink cold water from the fridge. You _________ (needn’t, can’t) worry so much. I’m sure he’ll be well soon. should ought to had better had better not needn’t should作为情态动词最基本的意思是“应该”——既可指有责任或义务 “应该”做某事，也可指建议或劝告某人“应该”做某事. ought to“应当；应该”,有一种责任和义务，强调客观要求。后接动词原形. 否定形式 ought not to. You’d better do sth 你最好做某事 You’d better not do sth 你最好不要做某事 need 做情态动词用，通常用在疑问句、否定句中， 否定形式为need not do sth. 【例1】—Could I look at your pictures?