过去完成进行时表述的是过去某个时间正在进行的动作，直到另一过去时间点还未结束。其结构为：主语 + had + been + doing。如：He had been studying for hours. 这个时态常用于描述持续到过去某个时刻的动作，如He had been waiting for two weeks.（等待了两周，直到之后才结束）。结构中的had随人称变化而变化，如He had been waiting.（主语为he）。

与过去完成时相似，过去完成进行时也用于描述过去正在进行的状态。例如：Up to that time he had been translating those books.（直到那时，他一直翻译那些书）或He had been writing the letter till two o'clock.（直到两点，他一直在写信）。

语法含义包括但不限于：

1）尚未完成：He had been writing the novel.（他还没有完成这部小说）。

2）企图：He had been studying the meaning of this proverb.（他试图理解这个谚语的含义）。

3）未得结果：We had been studying what our enemy had said.（我们一直在研究敌人所说的话，但未能理解）。

4）最近情况：He had been quarrelling with his wife.（最近他一直在与妻子争吵）。

5）反复动作：He had been asking me the same question.（他一直在问同一个问题）。

6）情绪：What had he been doing？（他最近在做什么？表现出不耐烦的情绪）。