判断依据

　　1. 由时间状语来判定：一般说来，各种时态都有特定的时间状语。与过去完成时连用的时间状语有：

　　( 1 ) by + 过去的时间点。I had finished reading the novel by nine o'clock last night.( 2 ) by the end of + 过去的时间点。We had learned over two thousand English words by the end of last term.( 3 ) before + 过去的时间点。They had planted six hundred trees before last Wednesday.

　　2. 由“过去的过去”来判定：过去完成时表示“过去的过去”，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。这种用法常出现在：

　　( 1 )宾语从句中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。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。When I got to the station, the train had already left.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：Where did you study before you came here?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…"We had hoped that you would come, but you didn't.

　　3. 根据上、下文来判定。I met Wang Tao in the street yesterday. We hadn't seen each other since he went to Beijing.

　　用法

　　1. 过去完成时表示一个动作或状态在过去某一时间或动作之前已经完成或结束，即发生在“过去的过去”。When I woke up, it had stopped raining.我醒来时，雨已经停了。(主句的动作发生在“过去的过去”)

　　2. 过去完成时是一个相对的时态，表示的是“过去的过去”，只有和过去某一时间或某一动作相比较时才使用它。He told me that he had written a new book. (had written 发生在 told 之前 )

　　3. 过去完成时需要与一个表示过去的时间状语连用，它不能离开过去时间而独立存在。此时多与 already ， yet ， still ， just ， before ， never 等时间副词及 by ， before ， until 等引导的短语或从句连用。Before she came to China, Grace had taught English in a middle school for about five years.Peter had collected more than 300 Chinese stamps by the time he was ten.

　　4. 过去完成时表示某一动作或状态在过去某时之前已经开始，一直延续到这一过去时间，而且动作尚未结束，仍然有继续下去的可能。By the end of last year, he had worked in the factory for twenty years. ( had worked 已有了 20 年，还有继续进行下去的可能)

　　Had done在虚拟语气中的运用(属于较特殊情况)：

　　(1)在虚拟条件句中的运用，此时的意思要根据语境而定，可以与虚拟语气一起来归纳。主要表示与过去事实相反的愿望，即与过去事实相反。If I I had taken your advice, I would have got a good grade in the exam.如果我听取了你的建议，我将会在考试中取得好的成绩。(had taken表明过去我没有采取建议)

　　(2)有expect，intend，suppose(假定)，hope,think等动词的过去完成时在句中出现时，表示未实现的打算，希望，愿望的意味。I expect that I had been an intern in that company.我希望我已经是那个公司的一名实习生。(同样地，我并不是这个公司的实习生)

　　(3)在If only(但愿，要是) or wish出现的虚拟语气中，同样也表示与过去事实相反的愿望，想法。Honestly,if only I had studied in university.说真的，要是我在大学学习多好!(事实上我没有，与现实相反)I wish I had been awarded the prize in the sports meeting.我希望我在运动会上被授予了奖励。(事实上获奖不存在)

　　在时间状语从句中的运用：

　　一些引导词 since, until, no sooner...than, hardly...when, scarcely...when 等，一般可视为 "had done" 出现的信号,从句常用一般过去时。No sooner had Whitney Houston began to sing a song than there was an instant sensation.惠特妮·休斯顿一开始唱歌，就引起了瞬时的轰动。(注意：这里由于no sooner 否定前置，句子谓语部分倒装，所以”had”提前)It was a long time since Darcy had lived in this city.达西住在这座城市已经有很长时间了。(达西在过去的某个时间点之前就住在这座城市)

　　重点

　　英语中，已经有了一个过去一般时表示在过去发生的动作，为什么还有过去完成时呢?要记住：过去完成时的关键概念是：假设在过去发生了两件(或以上)的事件，一件是A事件，另一件是B事件，如果A、B两个事件几乎是同时发生的，那就用一般过去时;但是，如果A、B两个事件不是同时发生的，怎么办呢?那就是：哪个事件先发生，就用过去完成时。在上面的假设中，如果A事件先发生，A就用过去完成时;如果B事件先发生，B就用过去完成时;而不管两件事是用什么样的时间状语或其它形式表示的。

　　例句：She said (that) she had never been to Paris.When the police arrived, the thieves had run away.We had hoped that you would come, but you didn't.Tom was disappointed that most of the guests had left when he arrived at the party.The students were writing, busily when Miss Brown went to get a book she had left in the office.

　　在上面的五个例子中，我们只要稍微分析一下，就可以发现：每个例子讲述的内容中，都包含着两个(或以上)在过去发生的事件。我们将两件事抽取出来看一下，就非常明白：必定有一件事是先生的，另一件是后发生的：……said…… had never been to (先没有“去”，后“说”)……arrived……had run away. (先“跑”了，后“到”)…… had hoped ……would come……didn't (先“希望”，后才发生“没去”)……was disappointed……had left ……arrived (先“离开”，后“到达”和“失望”)……were writing……went ……had left (先“离开”，后“到”和“写”)