什么是过去完成时？用法呢？

就是表示在过去的基础上已经做完的事

这种用法要有“参照”
for eg.

when he came into the room,i had already gone away

就是发生在过去的过去的事~
一般是 had+done/been...

表示过去完成的事情对过去的影响

过去里的完成的

例如：
I had played a game.
我过去玩过一个游戏

构成：过去完成时由"助动词had（通用于各种人称和数）+过去分词构成。

用法：过去完成时表示在过去某一时间或动作之前已经发生或完成了的动作。它表示动作发生的时间?quot;过去的过去"。与by、before等构成的短语连用。

Statements 陈述句

They had already had breakfast before they arrived at the hotel.

在他们到达旅馆之前，他们已经吃早饭了。

从句中"arrived at"到达在"过去"的时间，而"had already had"吃早饭的动作发生在到达之前，因此主句的时态为"过去的过去"。

I had finished writing my composition by 10:00 this morning. 今天上午10：00点以前，我已经写完了我的作文。

She had searched the internet for two hours when she found an ad for the Canon digital camera. 当她找到了佳能数码照相机的广告时，她已经在因特网上查询了两个小时。

I went over what I had written again and again so that I wouldn't mak