They had only been waiting for the bus a few moments when it came.他们只等了一会儿车就来了。 ②表示反复的动作
He had been mentioning your name to me. 他过去多次向我提到过你的名字。
You had been giving me everything. 你对我真是有求必应。
③过去完成进行时还常用于间接引语中（详见第12章）
The doctor asked what he had been eating. 医生问他吃了什么。
I asked where they had been staying all those days.我问他们那些天是待在哪儿的。
④过去完成进行时之后也可接具有“突然”之意的when 分句
I had only been reading a few minutes when he came in. 我刚看了几分钟他就进来了。
She'd only been reviewing her lessons for a short while when her little sister interrupted her. 她温习功课才一会儿，她妹妹就打断她了。
3．过去完成进行时和过去完成时的比较
She had cleaned the office, so it was very tidy.她已经打扫过办公室了，所以很整洁。（强调结果） She had been cleaning the office, so we had to wait outside.
她一直在打扫办公室，所以我们不得不在外面等着。（强调动作一直在进行）
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