有如下程序: #include <iostream> using namespace std; using namespace std; class Base{ public: void fun( ){cout<<'Base::fun'<<endl:} }; class Derived:public Base{ public: void fun( ){ eout<<'Derived::fun'<<endl: } }; int main( ){ Derived d; d.fun( ); return 0; } 已知其执行后的输出结果为: Base::fun Derived::fun 则程序中下画线处入的语句是