过去完成时表示"过去的过去"，即过去某个动作之前已经完成的动作。
要点讲解
- 结构：had + 过去分词。
- 用法：表示在过去某一时间或动作之前已经发生或完成的动作。
- 常与 by the time, by the end of + 过去时间, before 等连用：By the time I got there, the bus had left. 我到那里时，公交车已经开走了。
- 与 when/after 连用表示先后：When I arrived, the meeting had begun. 我到时会议已经开始了。
- hardly...when / no sooner...than 一……就……（主句用过去完成时）：Hardly had I got home when it rained. 我刚到家就下雨了。
- 过去完成时与一般过去时的区别：过去完成时必须有"过去的过去"作参照，不能单独使用。
- think/hope/expect 等词的过去完成时表示"本以为/本希望"（未实现）：I had hoped to see you. 我本希望见到你。
经典例句
- She said she had seen the movie before.
她说她以前看过这部电影。 - The train had left when we arrived at the station.
我们到车站时火车已经开走了。 - By the end of last term, we had learned 2000 words.
到上学期末，我们已经学了2000个单词。
易错提醒
- 过去完成时必须有过去时间/过去动作作参照；had done 是"过去的过去"。