英语就是这样( 81 ) Past continuous Tense 过去进行式Past Perfect tense过去完成式

过去进行式（Past continuous Tense）和过去完成式（Past Perfect tense）有什么不同？

过去进行式（Past continuous Tense）中，同时有两个动作发生；重点是某一事情在进行中(动作时间比较长)，突然另一事情(突兀性)发生了，出现了！

When there was a loud explosion, the football match was going on.

当足球比赛在进行事， 突然有一个巨大的爆炸声，。

I was waiting at the bus stop when the road caved in.

当道路在塌陷时，我正在车站等待公车。

It was raining heavily when the landslide happened.

大雨倾盆的时候发生了山崩。

过去完成式（Past Perfect tense）是描述两的动作的先后；一个动作完成后，另一动作紧接而来！

When I came to his house, he had left.

当我来到他家时，他已经离开了。

I had arrived before you (came).

我比你先来。

The goods had been sold out before the next consignment arrived.

在新的货物未到达之前，目前的存货已经销售一空了。

上面的句子，动作或事情的发生，一前一后有明显的分明！