形式

should / would have done sth.

用法

1、 過(guò)去將來(lái)完成時(shí)表示在過(guò)去將來(lái)某一時(shí)間以前發(fā)生的動(dòng)作，并往往會(huì)對(duì)過(guò)去將來(lái)某一時(shí)間產(chǎn)生影響。

I thought you’d have left by this time. 我想這會(huì)兒你已經(jīng)走了。

He told them he would have finished it by 8 o’clock. 他告訴他們他會(huì)在8點(diǎn)以前干完。

I guessed that Helen would have told her something. 我猜海倫會(huì)告訴她一些情況的。

2、 過(guò)去將來(lái)完成時(shí)還常用在虛擬語(yǔ)氣中，表示與過(guò)去的事實(shí)相反。