过去完成时用法

1、其结构为: had + 过去分词。如：I had finished my homework before he came.(在他来之前我已经完成了作业)He had left before I woke up.(他在我醒来之前已经走了)

2、过去完成时还可以与其他过去时间状语连用。如 by the time, by then, by the end of 等。例如:I had been studying English for five years by the time I went to America.(在我去美国的时候我已经学习英语五年了)By then, he had already left the city.(那时他已经离开了这个城市)