had been doing是过去完成进行时。
例句：
He asked me what I supposed he had been doing.
接着他又问那我认为他刚才在做什么。
I had been doing what youre almost certainly doing now.
我做的是你们肯定现在在做的。
扩展资料
Nobody knew what they had been doing all these years.
没有人知道他们这些年都在干什么。
Until this summer, China had been doing that carefully.
截止今年夏天，中国一直在审慎地这么做。
At that point, he realized what he had been doing all along.
在那时，他才意识到他一直在做的事。
