概念：过去将来完成时表示从过去观点看将来某时某动作业已完成。这个时态用得相对比较少，通常主要用于转述方面，即用于间接引语中。
结构：过去将来完成时由“would+have+过去分词”构成。
用法及用例
1、过去将来完成时表示在过去将来某一时间以前发生的动作，并往往会对过去将来某一时间产生影响。

I thought you'd have left by this time.

我想这会儿你已经走了。

He told them he would have finished it by 8 o'clock.

他告诉他们他会在8点以前干完。

I guessed that Helen would have told her something.

我猜海伦会告诉她一些情况的。

2、 过去将来完成时还常用在虚拟语气中，表示与过去的事实相反。
[注]在当代英语中，大家都用 would (缩略式为 'd)
3.过去将来完成时表示在过去看来将来某时会已经完成的动作：

She said she’d have finished her exams by then.

她说那时她会已经考完试了。

I thought Sophia would have told you something.

我想索菲娅会已告诉你一地情况。

I thought you would have finished by now.

我想你现在一定已经干完了。

There are a lot of things I should have liked to ask you.

有好些事我本想问你的。

He knew by the time he arrived she would have gone home.

他知道他到时她会已经回家了。

Well, well! Who would have guessed it!

真是的! 这谁会想到呀!