过去完成时

　　过去完成时用来表示过去某个时间或某个动作之前已经完成的动作，或者表示过去某个时间开始一直延续到过去另一个时间的动作。强调过去的过去。常和after , before , by , until 等引导的时间状语连用。过去完成时的形式是had + 动词过去分词。

　　When I came to her room , she had already left . 当我来到她房间时，她已离开那里了。

　　I waited until he had finished his work . 我一直等到他干完活。

　　1. 过去完成时通常与由介词“by + 表示过去时间的名词”构成的短语连用。例如：

　　By the end of last week we had already done half of the work. 到上星期为止，我们已经做了一半的工作了。

　　By the time I left the school I had taught that class for ten years. 到我离开学校的时候为止，我已经教了那个班十年了。

　　2. 过去完成时通常用在动词said, told, asked, explained, thought, wondered等引起的宾语从句中。例如：

　　I told them that I had done enough work for one day.

　　我告诉他们我这一天做的工作够多的了。

　　She wondered who had left the door open.

　　她想知道是谁没关门。

　　3. 在no sooner … than, hardly … when, scarcely … when, barely … when句型中，主句中的谓语动词通常要用过去完成时，从句中谓语动词要用一般过去时。例如：

　　Hardly had he begun to speak when the audience interrupted him.

　　他刚一开口说话，听众就打断了他。