Sentence transformation

[dungdinh2002]

Hi there.

Please help me on this:

I am not sure whether it is correct or not when rewriting the sentence: "I am sure they were not aware of the consequences." into "They CAN'T HAVE BEEN AWARE OF THE CONSEQUENCES". (I have read it at Rephrase - English). To me, it should be as follows :
They could have been aware of the consequences.

Could you please explain it in details? Thanks in advance.

[susiedqq]

I agree:

They could not have been aware of the consequences.