Question

过去完成式

Answer 1

过去完成时(The Past Perfect Tense)：表示过去某一时间或动作以前已经发生或完成了的动作，对过去的某一点造成的某种影响或是结果，用来指在另一个过去行动之前就已经完成了的事件。它表示动作发生的时间是“过去的过去”，侧重事情的结果。

用过去完成时造句：

1.I had stayed in Beijing for three years by then.

2.Until then he had known nothing about it. 

3.After he finished his homework,he went to bed.