（一）过去完成进行时

【构成】过去完成进行时的肯定形式为"had been +动词-ing形式"；否定形式为"had not been +动词-ing形式"。

【用法】

★过去完成进行时表示动作在过去某一时间之前开始，一直延续到这一过去时间，该动作可能刚刚结束，也可能还在继续。如：

When I first met Jane, she had been working in that school for 10 years.

She had been working all day, but she still hadn't finished it when I arrived.

★过去完成进行时还可以表示某动作在过去某段时间内反复进行而不是一次性发生。如：

He had been asking me the same question.

★过去完成进行时必须以一个过去的时间为前提，但若上下文语境充分，过去的时间可省略。如：

I had been studying for 2 hours when he called ten minutes ago.

At last they got the information they had been expecting.

★过去完成进行时还常用于间接引语中。如：

They said they had been having a match with Class One.

★过去完成进行时还可与具有"突然"意义的when从句（该从句用一般过去时）连用。如：

The planes had been planting seeds for nearly a month when it began to rain.

【拓展】过去完成进行时与过去完成时的区别：

　　过去完成进行时强调某个过去事件之前发生的、较长时间段内进行的动作，或过去某个时间段内反复进行或还在进行的动作；过去完成时表示过去某一时间之前已经发生的动作，或一个动作在另一个过去的动作发生前已经完成。如：

It had been snowing for several days. The ground was all covered with snow. （强调snow这一动作一直在进行）

She had cleaned the room, so it was very tidy. （强调打扫的动作已经完成）

【即学即练】选用括号内合适的内容完成下面句子。