新东方白易礼：英语四级考试语法笔记(四)

　　I don’t see how I could have done otherwise. 我看不出我当时还有别的做法。

　　Who could have supposed you were going to do such a thing? 谁会想到你会做出这样的事情。

　　Nobody could have foreseen such a calamity. 这样的灾祸谁也不会预想到。

　　(2)could have done(但不是can)在肯定句中，表示“那时本来可以…;差点就要…”，有时用来进行婉转地批评(与might同意，但语气更强一些)：

　　We could have solved the problem in a more reasonable fashion. 这个问题我们本来是可以更合理得解决的。

　　He could have told her, but he did not choose to. 他本来可以告诉她的，但他不愿这样做。

　　When she heard the news, she could have cried. 听了这消息，她简直要哭出来了。

　　I could have died laughing. 我简直要笑死了。

　　You could have been more considerate. 你其实可以想的更周到一些。

　　We could have started a little earlier. 我们其实可以更早一些动身的。

　　The result could have been better. 结果本可以更好一些。

　　5、should/ought to have done的含义。 “should/ought to have+过去分词”表示“过去应该做谋事却没有做”;“should not/ought not to have+过去分词”表示“做了不应该做的事”。含有责备或遗憾的意思。例如：

　　You shouldn’t /oughtn’t to have come here alone at such a late hour. 你这么晚的时候本不一该一个人来这里的。(实际是一个人来的)

　　She should/ought to have gone there alone. 她本该一个人去那里的。(实际上不是)

　　You should have come here ten minutes earlier. 你本应该早10分钟来才是。

　　The boy shouldn’t have been playing the piano. 那孩子不应该一直在弹钢琴。

　　6、might, may, must表示推测时的区别: may，might, must可表示 推 测“可能”.根据表示可能性的大小，我们把这三个词排列为：might

　　It might rain tomorrow. (将来)明天可能下雨。

　　They might be watching TV now. (现在)他们可能正在看电视。

　　Jane might have visited the Summer Palace last year. (过去)去年珍妮可能去过颐和园。

　　He may have something important to do. (现在)他可能有更重要的事要做。

　　They may have been to Shanghai last summer. (过去)去年夏天他们可能去过上海。

　　There must be something wrong with him. (现在)他肯定出问题了。

　　He must have made a mistake. (过去)他一定是犯了个错误。

　　第四部分 几个用法的区别

　　1、 can 和be able to的区别。can在表示“能力”时与be able to同义。但是can的时态形式不如be able to多。在一般将来时和现在完成时中只能用be able to。如：

　　She will be able to dance in a week. 她再过一星期就会跳舞了。

　　Nobody has ever been able to do it. 从来没有人能够做这事。

　　在过去时中，could表示具备某种能力，但不一定做事;而was able to表示努力设法去做谋事，成功后说明有能力，相当managed to do或succeeded in doing。这时，could和was able to是不能互换的。例如：

　　When he was a boy, he could swim across the river in fifteen minutes. 他小时侯，15分钟就能游过那河。(could表示能力，但不一定这么做)

　　He was able to swim across the river in fifteen minutes last week.

　　=He managed to swim across the river in fifteen minutes last week.

　　=He succeeded in swimming across the river in fifteen minutes last week.

　　上周他15分钟就游过了那河。(was able to表示真这样做了，而且成功了。这里不能用could)