the old woman was hit by a car while ----- the road.

cross是动词
后面省略了she was
The old woman was hit by a car while (she was) (crossing) the road.
老太太在过马路时被车撞了.
当...时,要用crossing表达进行
crossed前面要有主语,she cross时态不符
第一个答案写错了吧