过去完成时是一种英语时态，用来描述在过去某一时间点或动作之前已经发生或完成的动作或状态。以下是过去完成时的一些基本句型和用法：

肯定句

主语 + had + 过去分词

例句：He had finished his homework.

否定句

主语 + had + not + 过去分词

例句：He had not called me yet.

一般疑问句

Had + 主语 + 过去分词

例句：Had you been waiting for a long time？

特殊疑问句

特殊疑问词 + had + 主语 + 过去分词

例句：When had you arrived？

被动语态

主语 + had （not） + been + 过去分词

例句：The book had been written by a famous author.

时间状语

by the time （到...时为止）

例句：By the time I arrived, they had already left.

before （在...之前）

例句：Before I left, I had finished my homework.

after （在...之后）

例句：After I had eaten breakfast, I went to work.

其他用法

与when等从句连用：had + just / barely / hardly / scarcely + done...when...，no sooner...than...

表示持续到过去某时之前的动作或状态：We had finished the work by nine o'clock yesterday.

这些句型和用法可以帮助你更好地理解和运用过去完成时来描述复杂的过去时间顺序和状态。