50. You won’t be able to see him because he ______ a meeting in Suzhou when you arrive.

A．will have had

B．will be having

C．will have

D．is having

下面对于友元函数描述正确的是（ ）。

A．友元函数的实现必须在类的内部定义

B．友元函数是类的成员函数

C．友元函数破坏了类的封装性和隐藏性

D．友元函数不能访问类的私有成员