情态动词（复习篇）.pptVIP

1）?情态动词?除ought?和have?外，后面只能接不带to?的不定式。 2）?情态动词没有人称，数的变化，即情态动词第三人称单数不加-s/ed/ing。 3）?情态动词没有非谓语形式，即没有不定式，分词，动名词等形式。 情态动词的语法特征 情态动词主要有： 1）can/ could：否定或疑问的推测：不可能/可能吗 2)may/might：可能性的推测：可能 3)must ：肯定性的推测：想必 4)should/ought to ：应该 5)need(需要) /dare(敢)主要用在否定和疑问句中 6）shall/will/would在一定场合下也可以用作情态动词 1.can表示能力(体力或脑力) I can speak English while he can’t . What he said yesterday afternoon could not be understood by anyone present. 2.表示允许 Can I sit here?/You can sit here. 3.表怀疑（在否定句和疑问句中，表疑问、惊异、不想信等态度） Mr. Bush is on time for everything. How can it be that he was late for the opening ceremony? can/could (can表现在的能力，could表过去的能力) 4.表可能性（常出现在否定句中，如用在肯定句中则表示理 论上的一种可能性或有时候可能会 Even an experienced teacher can make mistakes. Shanghai can be very cold in March. （1）can表示推测“可能性”时，往往用于否定句或疑问 句。can’t“一定不”，can在疑问句中意思是“会、可能” He can’t be at home. = It is impossible that he is at home. 他一定不在家。（This can’t be true.） What can it mean? （2）can /can’t+ have done，表示对过去发生的动作进行推测。He can’t have gone to Shanghai for I saw him a minute ago. 他不可能去了上海，我刚才还看见他。It’s so late. Where can she have gone? 天晚了，她可能去哪儿了呢？ -----Look, someone is coming. Guess__________ .-----Jack. He’s always on time.A. who can it be B. who he mayC. who he can be D. who it can be can, could be able to 的区别 We’ll be able to finish the work soon. 1.can只用于现在式和过去式(could)。be?able?to可以用于各种时态。 2.can的主语是人或物,be able to的主语是人 She can/be able to sing the song in English. 3.表示特定的某一过去能力或表示成功地做了某事时，只能用was/were?able?to，?不能用could。 Although the soldier was badly wounded, he was able to tell what had happened. I haven’t been able to see the film. The computer can make you feel comfortable. She ran fast but she couldnt/ wasn’t able to catch the bus. may/might 1）表示询问征求别人意见或允许 -----May I come in?-----Yes,please. May I ask you a question? You may stay here as long as you like. 2)表示判断和猜测,”或许，可能”表示没有把握的推测（might不表示过去时态，只是语气上比may更委婉，表示的可能性更