形式
should / would have done sth.
用法
1、 過去將來完成時(shí)表示在過去將來某一時(shí)間以前發(fā)生的動(dòng)作,并往往會(huì)對(duì)過去將來某一時(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、 過去將來完成時(shí)還常用在虛擬語氣中,表示與過去的事實(shí)相反。