唔識幾時用past perfect tense,介紹一下超急

過去完成時表示在過去某一時間或動作以前已經完成了的動作。這個過去的時間可以用by, before 等介詞短語或另一個時間狀語從句來表示。

By the end of last year we had built up many new factories.
　到去年年底我們已建立了許多新工廠。
She had just gone out when I called at her house.
　我到她家時她剛出去。
When I had reviewed my lessons I took a rest.
　我複習完功課之後，休息了一會兒。
Lao Li told the children that he had suffered a great deal in the old days.
　老李告訴這些孩子們他在舊時代裏受過很多苦。過去完成時可以表示由過去某一時間開始，一直延續到另一時間的動作，常和 for (for 有時可以省去) 或 since 構成的短語或 since 引導的從句連用。

It rained yesterday after it had been dry for many months.
　在天旱了好幾個月之後昨天下雨了。
The old man died after he had been ill a long time.
　那個老人病了很長時間之後死去了。
He had been here once since six o'clock.
　六點以後，他來過這裏一次。在敘述過去時，過去完成時可用於追述或補敘更早以前發生的動作。 Nearly two years passed before Paul met Zhukhrai again. Paul had grown into
　　 man, grown up with shells bursting all around him, grown up in suffering and
discomfort. He had seen many terrible things. Together with thousands of others
like himself, burning with the fire of struggle for the power of their class, he had
marched from one side of the country to the other. He had become one of the
"organization of tough fellows" that Zhukhrai had talked to him about.

差不多過了兩年，保爾又遇見了朱赫萊。這時，保爾已長大成人，他是在
　　槍林彈雨中成長起來的，是在苦難與艱辛中成長起來的。他眼見過很多可
　　怕的事情。他和成千的和他一樣的人們一起，燃燒著為自己的階級的政權
　　而斗爭的火焰，從祖國的一邊轉戰到祖國的另一邊。他已參加了朱赫萊跟
　　他談過的那個“頑強的人們的組織”。 〔注〕當一個由before, after, as soon as等連詞引導的從句所表示的動作和主句的
　　　動作緊接時，由於這些連詞本身已經說明兩個動作發生的先後關系，因
　　　此兩個動作均可用“過去一般時”來表示。如：　　　We had breakfast after we did morning exercises. 做完早操後，我們吃早飯。
　　　He want home as soon as the meeting was over.會一結束，她就回家去了。http://www.louhau.edu.mo/www/teach/STUDENT/The%20Past%20Perfect%20Tense.htm

要有兩個行為,1先1後,而個後都用過去式,多數用喺故事/轉述句,用then/after/before連接.
例:The teacher asked the students that if/whether they had finished cleaning their classroom.(轉述句)
I had done a great job,then my teacher praised me.(故事)
He had killed his enemies before he died.(故事)