下列程序的执行结果是【 】。 include < iostream. h> class Myclass { public: void GetSum(int a) static int Sum: private: int A; }; int Myclass:: Sum =10; //必须在类外部对静态数据成员初始化 void Myelass: :GetSum(int a) { A=a; Sum+=A; } void PrintSum(Myclass& A) { cout<<'Sum='<<A.Sum<<end1; } void main( ) { Myclass M,N; M. GetSum(3) N. GetSum(7) PrintSum(M); }