过去完成时的讲解!要简洁,我刚接触过去完成时的!THANK YOU

过去完成时
The Past Perfect Tense
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 make any mistakes. 我一遍又一遍地检查了我所写的内容,以至我没有出现任何错误.
Negative 否定句
He remembered he hadn't paid for it yet. 他记得?挥懈犊睢?br> He said that he had never seen such a beautiful bird before.
他说他以前从来没有看过这样美丽的鸟.
Questions 疑问句
How many English flushed had you seen by the end of last term?
到上学期期末为止,你们看了多少部英文片?
Had you reached the station before ten o'clock?
到十点以前,你们已经到达火车站了吗?
过去完成时的构成
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.主要表
示过去某时前已发生的动作或情况（也可说是过去的过去）：
By the time I got there, it had already finished.
When I got to the check-out, I realized I had left my purse at home.
He said he had never seen such an exciting match before.
注：如果时间状语从句的动作发生在前,则从句用过去完成时,主句用一般
过去时.
When he had finished his work , he left his office .
After I had done my homework , I went to bed.