过去完成时注意：过去完成时表示过去某一时间或某一动作之前已经发生或完成的动作，动作发生的时间是过去的过去.它是一个相对的时态，只有在和过去某个时间或动作相比较时才会用到。 E.g. By the end of the match，they had kicked two goals. We had already had lunch before we arrived there. 其结构是had+过去分词.它的否定句是在had后边加not，变一般疑问句是把had提前。 E.g. I had reached the station before 9：00 oclock. I had not reached the station before 9：00 oclock. Had you reached the station before 9：00 oclock？ 它通常和before，by the end of 等引导的表示过去的时间状语连用。
