单选题 下面程序的结果是 #include＜iostream.h＞ class A { int a; public: A( ) :a(1) {} void showa ( ) {cout ＜ ＜ a;} }; class B { int a; public: B( ) :a(2) {} void showa( ) {cout ＜ ＜ a;} }; class C: public A, public B { t a; public: C( ) :a(3) {} void showa( ) {cout ＜ ＜ a;} }; void main( ) { C c; c.showa( ) ; }