2009年12月大學(xué)英語四六級考試語法精要(五)

　　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(shí)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(shí)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)�來某時之前業(yè)已完成的動作的推測�？勺g為，“可能”、“也許”、“想必”。

　　He would have arrived by now.

　　She would have recovered by then.