过去完成时的动作须在过去某一时间之前发生,即发生在“过去的过去”；

过去完成时的构成

过去完成时是由“had+过去分词”构成的.

例句：

Had he gone home when you arrived?

你到的时候他已经回家了吗?

By 5:00 yesterday morning we had done that work.

到昨天早上5点钟时,我们已经做完了那件工作.

The train (had) started before I reached the station.

在我到达车站之前,列车已经开了.

She said she had made much progress since she came here.

她说自从她到这儿后已取得了很大的进步.