作者：张树志
过去完成时的基本用法与现在完成时相似，所不同的是：现在完成时的动作须以现在为基准的以前，而过去完成时的动作须在过去某一时间以前完成，也就是说发生在"过去的过去"。
构成 助动词had＋动词的过去分词。had没有人称和数的变化,疑问句是把had提到句首，否定句是在had 后加not, had not可缩写为hadn't。
用法 （1）表示在过去某一时间或动作之前已经发生或完成了的动作，并产生了某种影响或结果。句中常见的时间状语有两种：
The rain had stopped and the air was clean. 雨停了，空气清新。
How many English words had you learnt by the end of last month? 到上月末，你已经学了多少英语单词？
We had reached the top of the mountain before midnight. 在半夜之前我们已经登上了山顶。
The roads were full of people. We hadn't foreseen that. 路上都是人。这是我们事先未料到的。
The film had already been on for half an hour when we got to the cinema. 当我们到达电影院时，电影已开演半小时了。
Mother had already cooked supper before I returned home. 在我回到家之前，妈妈已经做好饭了。
注意：如果时间状语从句中的动作发生在主句之前，则从句用过去完成时，主句用一般过去时。如：
After I had finished reading the novel, I went to sleep. 在我读完了这部小说之后，我才上床睡觉。
（2） 过去完成时还可以表示从过去某一时间开始，持续到过去的另一时间的动作或状态。往往与for, since引导的表示一段时间的短语或从句连用。如：
Mr Wang had taught in our school for six years before I came here. 在我来到这儿以前，王老师已经在我们学校任教6年了。
We had then been without sleep for twenty-four hours. 这时我们已有２４小时没有合眼了。
She had nursed her father in that room since she came back. 自从她回来就在那个房间里照顾她的父亲了。