We have been accused of exaggerating before,but unfortunately all our reports proved to be true.
我们曾被指责夸大其词,但遗憾的是,我们所有的报告都证明是真实的.
In the past this process of transition has often proven difficult.
在过去,这种转变过程常证明是艰难的.
prove是个系动词意思是“证明是……”,后面可以加to be也可以不加的.没有被动式的.
What he had said proved to be true.他所说的证明是对的.