1）过去完成时的定义: 动词的一种时态形式，表示到过去某一时间已经完成的行为或动作。 2）结构：had + 动词的过去分词3）时间状语：by...; for...; since... 等等。4）例句：He had finished his homework by 9 o'clock last night.He had waited there for three hours by that time.He had always stayed in his office ever since that morning....
