Professor Williams keeps telling his students that the future _____ to the well-educated. [ ]

A. belongs

B. is belonged

C. is belonging

D. will be belonged

假定要对类AB定义加号操作符重载成员函数，实现两个AB类对象的加法，并返回相加结果，则该成员函数的声明语句为______ 。

A．AB operator+(AB &a, AB &

B．AB operator+(AB &

C．opemtor +(AB

D．AB &operator+ ()