过去完成式的形式如下：

had + past participle

过去完成式是不能单独用的。我们用的时候，必须有另一个事件。也就是说，假如我们有两件事 A 和 B，两件事都发生在过去，但 A 发生在 B 以前，A 应该用过去完成式，B 则用过去式。以下是几个例子：

(1) 他到台湾以前，曾学过中文。

He had studied Chinese before he came to Taiwan.

(2) 他念大学以前，曾前工作过。

He had worked before he decided to go to college.

(3) 我写这篇有关爱尔兰的小说以前，曾去过爱尔兰。

I had been to Ireland before I wrote this book about Ireland's people.

(4) 我在上大学以前，已经学过微积分。

I had studied calculus before I got into college.

(5) 周一以前，已经下过雪了。

It had already snowed before Monday.

如果我们要强调较早发生事件的连续性，我们可以用过去完成进行式。占去完成进行式和现在进行式惟一不同的地方是 verb to have 的地方一定要用had 。以下是一些过去完成进行式的例子：

1. I had been watching TV before you called me.

2. I had been working hard in a company for many years before I went to college.

3. He had been studying before he went to class.

4. He had been driving all day before he went to sleep.