二、用法：
have加过去分词表示动作发生在过去对现在的影响
had加过去分词是指过去某一动作之前已经发生或完成的动作，即动作有先后关系，动作在前的用过去完成时，在后的用一般过去时。
三、常用时间状语：
have加过去分词
1、表示到现在为止：already ,yet ,just ,ever, never ,before ,since ,so far, until now ,by now ,up to now.
2、表示最近：recentl,lately in the past/last few years
3、包含现在在内的时间状语：this morning/afternoon,all the year ,all day
had加过去分词
分两种情况：
由时间状语来判定
与过去完成时连用的时间状语有：
1、如：I had finished reading the novel by nine o'clock last night.
2、如：We had learned over two thousand English words by the end of last term.
3、 before + 过去的时间点。
如：They had planted six hundred trees before last Wednesday
由“过去的过去”来判定。
1、当宾语从句的主句为一般过去时，且从句的动作先于主句的动作时，从句要用过去完成时。在told, said, knew, heard, thought等动词后的宾语从句。
如：She said that she had seen the film before.
2、状语从句中
在时间、条件、原因、方式等状语从句中，主、从句的动作发生有先后关系，动作在前的，要用过去完成时，动作在后的要用一般过去时。
如：After he had finished his homework, he went to bed.
注意： before, after 引导的时间状语从句中，由于 before 和 after 本身已表达了动作的先后关系，若主、从句表示的动作紧密相连，则主、从句都用一般过去时。
如：After he closed the door, he left the classroom.
3、表示意向的动词，如hope, wish, expect, think, intend, mean, suppose等，用过去完成时表示"原本…，未能…"
如：We had hoped that you would come, but you didn't.