A.过去完成时和过去完成进行时
过去完成时:I had taken a bus into town.
过去完成进行时: I had been swimming in the pool
B.形式
positive form: I had been waiting ages.
negative: I had not been waiting ages.
question: had it been raining?
C.I had been doing or I had done?
had been doing:持续一段时间,通常接时长短语,通常不用于表示状态 When the company went bankrupt ,it had been losing money for months.
had done:已经完成,通常接量词短语,可以拥有表示状态 When the company went bankrupt,it had lost over a million pounds.
D.同其他时态比较
现在完成时和过去完成进行时
Vicky looks very upset.I think she's been crying.
Vicky looked very upset.I shought shed'd been crying.
过去进行时和过去完成进行时
When I phoned,Natasha was having a piano lesson.
When I phoend,Natasha had been having a piano lesson.