过去将来完成时，顾名思义，是在过去的时间点上谈论未来将会完成的动作。不是特别常用的一种时态。基本结构为：would + have + done（过去分词）。

例如：
John left for the front; by the time he should return, the field would have been burnt to stubble.
约翰离开了；等他回来的时候，恐怕田地已经被烧光了。

在过去发生的事这个大前提下，此处的时间点关系：约翰离开了——田地烧了起来——约翰回来（田地已经烧光）。

过去将来完成时一般应用于以下两种情况：

1、 间接引语
例句：
1）He said he would have done with my camera by the end of next month.
他说到下月底就不用我的照相机了。

2）He knew by the time he arrived she would have gone home.
他知道他到时她会已经在家。

3）I guessed that Mother would have made some sandwiches by the time we got back.
我猜我们回来时妈妈已经做好一些三明治了。

2、 虚拟句
例句：
1）But I also know that if I could somehow go back, I probably would have done the same thing.
其实我很清楚，如果给我一次重来的机会，我或许还是会做出同样的选择。

2）“If it was possible, I would have done it, ” Kostya said.
“要是能做到的话，我肯定会按你说的那么做。” 克斯特亚说。

3）If I refused a customer or a customer complained about me they would have done something bad to me.
如果我拒绝了一个客人或者客人有抱怨，他们会惩罚我。