专门替中国人写的英语语法4-3：过去完成进行式（Past Perfect Progressive Tense）

　　4-3 过去完成进行式(Past Perfect Progressive Tense)

　　过去完成式的形式：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。

　　过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.