A 形式

to have been+现在分词：

He seems to have been spying for both sides．

他似乎一直在为两方面搞秘密情报。

B 用法

主要用于助动词之后和appear，seem之后，但也可以用在happen， pretend以及believe， know， report， say， understand的被动式之后：

—He says he was talking to Tom．

—He couldn’t have been talking to Tom．Tom wasn’t there．

—他说他当时在跟汤姆说话。

—他当时不可能在和汤姆说话。汤姆当时不在那里。

—I was following Peter closely¹．

—You shouldn’t have been following him closely；you should have left a good space between the two cars．

—当时我正紧紧地跟着彼得。

—你不应该紧跟着他；而应该使两车之间保持相当的距离。

He appears to have been waiting a long time．相当于：

It appears that he has been waiting a long time．

看来他已经等了很久了。

He pretended to have been studying．相当于：

He pretended that he had been studying．

他假装一直在学习的样子。