I don’t see how I could have done otherwise. 我看不出我當時還有別的做法。

　　Who could have supposed you were going to do such a thing? 誰會想到你會做出這樣的事情。

　　Nobody could have foreseen such a calamity. 這樣的災禍誰也不會預想到。

　　(2)could have done(但不是can)在肯定句中，表示“那時本來可以…;差點就要…”，有時用來進行婉轉地批評(與might同意，但語氣更強一些)：

　　We could have solved the problem in a more reasonable fashion. 這個問題我們本來是可以更合理得解決的。

　　He could have told her, but he did not choose to. 他本來可以告訴她的，但他不愿這樣做。

　　When she heard the news, she could have cried. 聽了這消息，她簡直要哭出來了。

　　I could have died laughing. 我簡直要笑死了。

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

　　We could have started a little earlier. 我們其實可以更早一些動身的。

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

　　5、should/ought to have done的含義。 “should/ought to have+過去分詞”表示“過去應該做謀事卻沒有做”;“should not/ought not to have+過去分詞”表示“做了不應該做的事”。含有責備或遺憾的意思。例如：

　　You shouldn’t /oughtn’t to have come here alone at such a late hour. 你這么晚的時候本不一該一個人來這里的。(實際是一個人來的)

　　She should/ought to have gone there alone. 她本該一個人去那里的。(實際上不是)

　　You should have come here ten minutes earlier. 你本應該早10分鐘來才是。

　　The boy shouldn’t have been playing the piano. 那孩子不應該一直在彈鋼琴。

　　6、might, may, must表示推測時的區別: may，might, must可表示 推 測“可能”.根據表示可能性的大小，我們把這三個詞排列為：might

　　It might rain tomorrow. (將來)明天可能下雨。

　　They might be watching TV now. (現在)他們可能正在看電視。

　　Jane might have visited the Summer Palace last year. (過去)去年珍妮可能去過頤和園。

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

　　They may have been to Shanghai last summer. (過去)去年夏天他們可能去過上海。

　　There must be something wrong with him. (現在)他肯定出問題了。

　　He must have made a mistake. (過去)他一定是犯了個錯誤。

　　第四部分 幾個用法的區別

　　1、 can 和be able to的區別。can在表示“能力”時與be able to同義。但是can的時態形式不如be able to多。在一般將來時和現在完成時中只能用be able to。如：

　　She will be able to dance in a week. 她再過一星期就會跳舞了。

　　Nobody has ever been able to do it. 從來沒有人能夠做這事。

　　在過去時中，could表示具備某種能力，但不一定做事;而was able to表示努力設法去做謀事，成功后說明有能力，相當managed to do或succeeded in doing。這時，could和was able to是不能互換的。例如：

　　When he was a boy, he could swim across the river in fifteen minutes. 他小時侯，15分鐘就能游過那河。(could表示能力，但不一定這么做)

　　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分鐘就游過了那河。(was able to表示真這樣做了，而且成功了。這里不能用could)