have+been是现在完成时，have been 已经；

所以用现在完成时，结构是have+过去分词(done)had+done是过去完成时，表示在过去这个时间点以前什么事情已经完成了；

例如：

I had done my homework before I went bed yesterday.

扩展资料

We took it as read that he must have been a KGB agent

我们完全相信他曾经是一名克格勃特工。

There have been some problems but basically it's a good system.

虽然出现过一些问题，但这基本上仍不失为一个好系统。

His family have been a very positive influence on him.

他的家庭对他有十分良好的影响。

There have been many changes in recent years.

近几年发生了许多变化。