13. 表示猜測的幾種不同的方法及意義

一些情態(tài)動詞與動詞的完成式連用能夠表示對過去情況的猜測或者未實現(xiàn)的可能性。

1） could have + 過去分詞

A. 表示對過去可能發(fā)生的事情的推測，意為，“可能做了某事”。

He couldn’t have seen her yesterday.

They could have lost their way.

B. 表示某事在過去本有可能發(fā)生，但事實上并未發(fā)生，意為，“本可以做某事”。

We could have started a little earlier.

I could have killed her. It was a narrow escape.

2） may （might） have + 過去分詞

A. 表示對過去情況的推測，意為，“可能已做某事”。

He may have heard the news.

I might have come to a wrong conclusion.

B. 表示一種未實現(xiàn)的可能性，即本可以做某事，而實際上并沒有做，有時含有抱怨的口吻。

It was a narrow escape. You might have killed yourself.

A lot of men died who might have been saved.

3） must have + 過去分詞

表示邏輯上的必然性，即按照某些現(xiàn)象推斷過去肯定發(fā)生過的某事。

She must have made a big mistake.

The city at one time must have been prosperous， for it enjoyed a high level of civilization.

4） needn’t have + 過去分詞

表示過去不必做某事，但已經(jīng)做了，即本可不必做某事。

You needn’t have woken me up. I don’t have to go to work today.

He needn’t have watered the flowers， for it is going to rain.

5） should / ought to have + 過去分詞

表示過去應(yīng)該做某事而實際上沒有做。

You should / ought to have done what your parents told you. （But you failed to do it.）

You should / ought to have been more careful. （But you weren’t.）

6） shouldn’t / oughtn’t to have + 過去分詞

表示過去不應(yīng)該做某事而實際上卻做了。

You shouldn’t / oughtn’t to have crossed the road when the lights were red. （But you did.）

They shouldn’t / oughtn’t to have left so soon. （But they did.）

7） would have + 過去分詞

表示對現(xiàn)在或?qū)砟硶r之前業(yè)已完成的動作的推測。可譯為，“可能”、“也許”、“想必”。

He would have arrived by now.

She would have recovered by then.