过去完成时
过去完成时是一个动词时态，用来表示过去发生的动作，并在另一个动作之前完成。
我们用过去完成时来表示从过去开始并持续到过去某一特定时间的事情。过去完成时和现在完成时的用法相同，但它指的是过去的时间，而不是现在。
以下是对过去完成时含义的描述:
- She didn’t want to move. She had lived in Milan all her life.
- After we had purchased tickets, we were able to enter the venue.
过去完成时通常与一般过去时一起使用，用来谈论发生在过去不同时间的两个或两个以上的事件。在这种陈述中，一般过去时描述了最接近说话时间的事件。过去完成时描述的是更早以前的事件。为了表示这一动作序列，经常使用介词“after”和“before”。
- The train had left (过去完成) before we arrived (一般过去) at the station. (The train left earlier and we arrived later).
- Anthony had gone (过去完成) to the university when I knocked (一般过去) on his door.
- He had cooked (过去完成) dinner before Gwen got (一般过去) back from work.
怎样构成过去完成时
做过去完成时，其结构为:
had 动词的过去分词
要做过去完成时，使用:
had 动词的过去分词形式
在下面的例子中，即使一般过去时动作在句子的前面，它仍然发生在后:
- The traffic was bad because a car had broken on the road.
- When we arrived at the stadium, the game had already started.
何时用过去完成时
过去完成时用来表达以下含义。
一个在第二点之前完成的动作
- After we had repaired the car, we went to the seas.
- When we arrived, the movie had already started.
在过去某个时间点之前的持续时间的动作。
- When Sarah graduated, she had been in Berlin for six years.
- On the 20th of May, I’d worked here for six months.
过去不真实的或想象的事物（虚拟语气的用法， 请参见英语的虚拟语气。）
- If I had known you were ill, I would have visited you.
- She would have passed the exam if she had studied harder.
- I wish I hadn’t gone to bed so late!
