在英语语法16多种时态中，过去将来完成时是用的相对较少的一种时态，它表示从过去观点看将来某时某刻某个动作已经完成的一种状态。通常主要用于转述方面，即用于间接引语中。
过去将来完成时基本形式：should / would have done sth.例句：
1. I would have left the building before the murder took place.
在谋杀发生的时候，我就已经离开了这座楼。

2. I thought you would have left by this time.
我想你这会儿已经走了。

3. I would have eaten the breakfast before my friends came in.
在我朋友进来的时候，我已经吃完早饭了。

4. I thought you would have done your homework as soon as possible.
我认为你应该尽快完成作业。

5. I would have finished this project before my boss called me.
在老板给我打电话的时候，我就已经完成了这个项目。

6. I thought you would have fed this litter cat.
我认为你应该喂养这只小猫。