using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{

    abstract class A1
    {
        public abstract void method();
    }


    class A2 : A1
    {
        public override void method()
        {
            Console.WriteLine("a2");
        }
    }

    class A3 : A2
    {
        //这里已经不能再override或什么了
        public override void method()
        {
            Console.WriteLine("a3");
        }
    }


    class Program
    {
        static void Main(string[] args)
        {
            A1 a2 = new A2();
            a2.method();
            A1 a3 = new A3();
            a3.method();
        }
    }
}

------解决方案--------------------
怎么可能呢，只是vs没提示让你重载而已，因为父类已经实现了