英语语法过去完成时的被动语态的知识点
过去完成时的被动语态的概念：
过去完成时的被动语态是过去完成时态和被动语态的叠合。表示过去某一时间以前已经完成的动作，常与by，before等引导的时间状语连用。由“had+been+过去分词”构成。
1）过去完成时的被动语态的肯定式为：had + been + done。
如：The task had been finished before 12:00 yesterday.
2）过去完成时的被动语态的'否定式为：have / has + not + been + done。
如：The task hadn't been finished before 12:00 yesterday.
3）过去完成时的被动语态的一般疑问句需将had提到主语的前面。
如：Had the task been finished before 12:00 yesterday?
4）过去完成时的被动语态的特殊疑问句为：疑问词 + had+ been + done。
如：What time had the task been finished yesterday?
过去完成时被动语态的用法：
过去完成时由“had+过去分词”构成，表示在过去某一时刻或某一动作之前发生的动作或状态，句中常用by，before，until，when等词引导时间状语。
如：We had built five new buildings by the end of last year. 过去完成时的被动语态有以下三种形式：
（1）肯定结构：主语＋had been done＋其他成分
（2）否定结构：主语＋had not been done＋其他成分
（3）疑问句结构：had＋主语＋been done＋其他成分；
疑问词＋had＋主语＋been done＋其他成分
过去完成时的被动语态常用于以下情况：
（1）表示过去某一时间以前已经完成的动作，常与by, before等引导的时间状语连用。
如：By the time he got to the school, the first period had been finished.
The classroom hadn't been cleaned before the teacher came.
How many buildings had been destroyed when the hurricane ended?
Had the new plan been discussed before the meeting?
（2）在told, said, knew, heard, thought等动词之后的宾语从句中，若表示过去某一被动动作时，用过去完成时。
如：The said the production costs had been reduced.
The boy was reminded that his homework had not been handed in.
The media reported more than 1,000 people had been killed in the earthquake.
（3）根据语意可以判断出动作先后的被动语态，用过去完成时。
如：As the assignment had been done, he went on to search the Internet.
He did what he had been told to.
另：当从句由after，before，when或assoonas引导时，主句和从句都可以用一般过去时。
如：When he arrived, he called her.
They locked the door before they left.
过去完成时与现在完成时被动语态用法区别：
现在完成时被动语态表示相对于现在来说已被完成的动作，过去完成时被动语态表示相对于过去某一时刻来说已被完成的动作。
例如：This polluted river has been cleaned. 这条被污染了的河流已被净化。
析：该句表示到现在为止这条河流已被净化。
例如：He said this book had been translated into Japanese. 他说这本书已被译成日语。
析：该句表示到他说话时所体现的时间为止这本书已被译成日语。
