我给你区分一下好了第一次我也没细看我估计他是这么个意思第一句I am not sure ........would have done.第二句直接到完。第一句不用改，第二句改成we are all waiting to be granted for tomorrow's attendence if they know they would be there or not
感觉楼主的句子是这样的。I'm not sure what others would have done( had they known that they wouldn't be here for the tomorrow that we all take for granted).后面括号扩起来的是不是if they had known that…后面是if 从句省略if把had提前了
