过去完成进行时

过去完成进行时相应于现在完成进行时，但涉及比「过去」还要更早的时间。至于现在完成进行时，我们更强调过程。

Had you been waiting long before the taxi arrived?
We had been trying to open the door for five minutes when Jane found her key.
It had been raining hard for several hours and the streets were very wet.
Her friends had been thinking of calling the police when she walked in.

这个型态也用于转述句。相当于直述句中的过去进行时和现在完成进行时：

Jane said, "I have been gardening all afternoon." = Jane said she had been gardening all afternoon.
When the police questioned him, John said, "I was working late in the office that night." = When the police questioned him, John told them he had been working late in the office that night.

过去完成进行时是由两个要素构成——Be 动词的过去完成时 (=had been) + 现在分词（动词原型+ing）。