What worried the child most was____to visit his mother in hospital.A.his not being allowed B.having not been allowed为什么一定要加his?什么情况下可以不用加his?

问题描述:

What worried the child most was____to visit his mother in hospital.
A.his not being allowed B.having not been allowed
为什么一定要加his?什么情况下可以不用加his?