using System;

public class Program

{

   public static void Main(string[] args)

    {

        A obj = new B();

        obj.Show();

        Console.ReadLine();

    }

}

class A

{

    public virtual void Show()

    {

        Console.WriteLine("A.Show()");

    }

}

class B : A

{

    public override void Show()

    {

        Console.WriteLine("B.Show()");

    }

}

​