下列选项中，关于接口的定义正确的是？ A: abstractclassDemo1{abstractvoidspeak();abstractvoideat();} B: interfaceDemo2{voidspeak();voideat();} C: interfaceDemo3{voidspeak();voideat(){};} D: interfaceDemo4{voidspeak(){System.out.println("ITCAST");}voideat();}

阅读下列程序,程序的运行结果是____。 #include usingnamespacestd; classAnimal { public: voidspeak(){cout<<"animallanguage!"<<endl;} }; classCat:publicAnimal { public: voidspeak(){cout<<"catlanguage:miaomiao!"<<endl;} }; intmain() { Catcat; cat.speak(); }