看看输出吧

class A    {        public A()        {            PrintFields();        }        public virtual void PrintFields()        {        }    }    internal class B : A    {        int x = 1;        private int y;        public B()        {            y = -1;        }        public override void PrintFields()        {            Console.WriteLine("x={0},y={1}",x,y);        }    }    class Program    {        static void Main(string[] args)        {            B b= new B();         }    }