class animal{public animal(){};private string name;public animal ( string name){this.name=name;}public virtual void show(){console.writeln("我叫：{0}",name);}} class people:animal{protected animal an;punlic void decorate(animal an ){this.an=an;}public override void show(){.........}} 我不太明白protected animal an;punlic void decorate(animal an ){this.an=an;}寫這段代碼有什么作用