请问老师 对He’s swimming across the river.中的river和across the rive

请问老师 对He's swimming across the river.中的river和across the river 怎么分别提问呢?
如题,

这种题目有点怪怪的啊.
如果对across the river划线提问,则答案为：
Where is/was he swimming?
如果是对the river划线提问,则答案只能写成：
What place is/was he swimming across?
注：/ 表示可以任意选用其一.