高中英语语法情态动词（28张PPT）

1. can -could ①表示能力,可能性 ②表示许可、请求, 常译为“可以” ③表示说话人的猜测，用来表达惊异、怀疑、 不相信等态度，主要用于疑问句和否定句 I can speak English. He could write music when he was four. 与过去有关的能力 更客气、委婉 惊异 怀疑 不可能、不相信 Can I use your dictionary? Could I see your passport? I believe her. She can’t be such a girl. What can the children be doing? The ground isn’t wet. It can’t have rained last night. [注意]can与be able to的区别 a. can常指现在,be able to 用于多种时态。 They will be able to tell you the news soon. b.过去式含义不同： was / were able to 设法做成某事 (managed to do sth. / succeeded in doing sth.) could仅表示有可能、 能够做某事, 事实上不一 定去做。 Most people were able to escape from the burning building. I’m afraid I couldn’t arrive on time. 2. must ① 表示“必须，应该”否定回答时常用needn’t或don’t have to. Must I go there in person? 我必须亲自去吗？ We must always follow the Party.我们要永远跟着党走。 ②表示“必然” All men must die.人总是要死的。 ③表示推测，“准是”、“一定”，否定形式为can’t She must be at home now.她现在准在家。 He must have told you that yesterday. 昨