using System;

public class Program

{

    public static void Main()

    {

        Derived1 a = new Derived1();

        Base b = new Derived1();

        Base c = new Derived2();

        Console.WriteLine("Derived1 as Derived1: "+ a.X());

        Console.WriteLine("Derived1 as Base: " + b.X());

        Console.WriteLine("Derived2 as Base: " + c.X());

    }

}

​

    public class Base {

​

        public virtual string X() {

            return "Base";

        }

    }

    public class Derived1 : Base

    {

        public new string X()

        {

            return "Derived 1";

        }

    }

    public class Derived2 : Base 

    {

        public override string X() {

            return "Derived 2";

        }

    }