1. 表示“过去的过去”，这是过去完成时最本质的用法，它既可表示过去某个时间或动作之前所发生的情况，也可表示过去某个时间或动作之前一直在持续的情况。如：

He had left when I arrived. 当我到达时他已经离开。

By six o’clock he had worked twelve hours. 到6点钟时他就已工作了12小时。

2. 表示过去未曾实现的想法，通常连用的动词是 hope, think, plan, mean, expect, intend, suppose 等。如：

I had meant to go on Monday but have stayed on. 我本想礼拜―走的，但又留下了。

I had hoped to send him a Christmas card, but I forgot to do so. 我本来希望寄给他一张圣诞卡的，但我忘了寄了。

He had intended to make a cake. but he ran out of time. 他原来打算做块蛋糕，但是没时间了。

I had thought the room to be empty but found it occupied. 我本以为这个房间是空着的，原来里面有人。

3. 在hardly [scarcely, barely]…when [before]…和no sooner…than…等句式中，主句通常要用过去完成时，而从句则通常要用一般过去时。如：

I had scarcely closed my eyes when the phone rang. 我刚合上眼电话铃就响了。

Mr Jenkins had hardly begun his speech, when he was interrupted. 詹金斯先生刚开始讲话就被人打断了。

She had no sooner opened the door than a cat jumped out from behind the door. 她刚刚门打开，一只猫就从门后跳了出来。