过去完成进行时

过去完成进行时
过去完成进行时的基本用法
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。动作是否继续下去，概由上下文而定。和过去完成时一样，过去完成进行时也必须以一过去时间为前提。如：

I had been looking for it for days before I found it. 这个东西，我找了很多天才找着。

They’d only been waiting for the bus a few moments when it came. 他们只等了不多一会儿，公共汽车就来了。

The telephone had been ringing for three minutes before it was answered. 电话响了三分钟才有人接。

如果上下文清楚，过去时间也可省去。如：

He was tired. He’d been working all day. 他累了。他工作了一整天。

The doctor asked what he had been eating. 医生问他吃什么来着。

过去完成进行时还常用在间接引语中，如：

The doctor asked what he had been eating. 医生问他吃什么来着。

过去完成进行时后接when从句
和过去完成时一样，过去完成进行时亦可后接具有“突然”意义的when从句（此句用过去一般时）。如：

I had only been reading a few minutes when he came in. 我刚看了几分钟书他就进来了。

She’d only been studying her lesson for ten minutes when her little sister interrupted her. 她温习功课不过十分钟，她的小妹妹就把她打断了。