一、基本用法
过去完成时的构成为“had＋过去分词”，主要用法如下：
(1)表示某一动作或存在的状态发生在过去某一时间或某一动作之前，即“过去的过去”。
By the end of last week, they had finished the work.
到上周末为止，他们已经完成了工作。
When Jack arrived, he learned Mary had been away for almost an hour.
当杰克到达时，他得知玛丽已经离开快一个小时了。
[名师指津] 过去完成时常常用在宾语从句中，从句谓语动作发生在主句谓语动作(过去时)之前。
She said that she had finished her homework.
她说她已经完成家庭作业了。
(2)某些动词的过去完成时表示过去未实现的希望、计划或打算。常用的动词有hope, expect, suppose, think, want, wish等。
They had wanted to help but couldn't get here in time.
他们本来想要来帮忙的，但未能及时赶到这儿。
I had hoped to send him a Christmas card, but I forgot to do so.
我本来想送他一张圣诞节贺卡，但把这事给忘了。
