would/should+have+過去分詞，這是虛擬語氣的一種用法。would have done表示對(duì)過去事情的假設(shè)，意思是“本來會(huì)做”。

have done的用法

1、should/ought to have done的含義.“should/ought to have＋過去分詞”表示“過去應(yīng)該做謀事卻沒有做”； “should not/ought not to have＋過去分詞”表示“作了不應(yīng)該做的事”. 含有責(zé)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(shí)候本不一該一個(gè)人來這里的.（實(shí)際是一個(gè)人來的）

She should/ought to have gone there alone.她本該一個(gè)人去那里的.（實(shí)際上不是）

2、would have done的含義.would have done“本愿意做某事”,非虛擬語氣時(shí),就是would 情態(tài)動(dòng)詞加動(dòng)詞原形，have done 就是現(xiàn)在完成時(shí),所以和起來 就是將來完成時(shí)的用法，過去將來完成時(shí)表示在過去看來將來某時(shí)會(huì)已經(jīng)完成的動(dòng)作。

例如：She said she’d have finished her exams by then.她說那時(shí)她會(huì)已經(jīng)考完試了。

He knew he arrived she would have gone home.他知道他到時(shí)她會(huì)已經(jīng)回家了。

3、must have done的含義.“must have＋過去分詞”表示對(duì)過去的推測(cè),意思是“一定已經(jīng),想必已經(jīng),準(zhǔn)是已經(jīng)….”,只用于肯定句中.例如：

He must have been drinking beer.他肯定一直喝啤酒來著。

若要表示否定,要用“can’t/couldn’t+ have+過去分詞”,意思是“不可能”：

The money can’t have been lost there.錢不可能是在那兒丟的。

should have done“本應(yīng)該做某事”

might have done“可能做過某事”

could have done“本可以做到某事”

would have done“本愿意做某事”