He had gone to bed by 10:00 last night.
When he was in Beijing,he visited places where he had played as a child.
It took me a long time before I was able to fully appreciate what they had done for me.
在过去的某个时间或动作以前已经发生的动作或已经存在的状态
I met Jim last week . We hadn't met each other since we left Japan.
从过去的某一时间开始，一直延续到过去另一时间的动作或状态。
I had hoped to send Peter a gift ,but I couldn't manage it
未曾实现的想法，还有suppose,expect,intened,mean
I'd(would) rather you hadn't been present
If only we had listened to their adviced
The game had hardly begun when it started raining
Hardly had I opened the door when he told me that
He had no sooner bought the car than he sold it
It was the second time he had been out with her
