Poly practice per Zack for me from here: http://tutorials.csharp-online.net/Inheritance_and_Polymorphism%E2%80%94Exercises

poly.cs

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

/*
 *  Polymorphism practice.  Doing exercises selected by Zack for me.
 *  http://tutorials.csharp-online.net/Inheritance_and_Polymorphism%E2%80%94Exercises
 * 
 */

namespace ConsoleApplication4
{
    class Program
    {
        static void Main(string[] args)
        {
            ElectronicTelephone et = new ElectronicTelephone();
            Console.WriteLine( et.Ring() );
            Console.ReadLine();

        }
    }

    abstract class Telephone
    {
        protected string phonetype;

        public abstract string Ring()
        {
            return "Ringing the " + phonetype;
        }

    }

    class ElectronicTelephone : Telephone
    {

        public ElectronicTelephone()
        {
            phonetype = "Digital";
        }

        public override string Ring()
        {
            return "Da " + phonetype + " makes funky noises.";
        }

    }

    class DigitalPhone : Telephone
    {
        public override string Ring()
        {
            throw new NotImplementedException();
        }
    }

    class TalkingPhone : Telephone
    {
        public override string Ring()
        {
            throw new NotImplementedException();
        }
    }
}