using System;  

public class Animal{  

    public virtual void eat(){  

        Console.WriteLine("eating...");  

    }  

}  

public class Dog: Animal  

{  

    public override void eat()  

    {  

        Console.WriteLine("eating bread...");  

    }  

}  

public class TestPolymorphism  

{  

    public static void Main()  

    {  

        Animal a= new Dog();  

        a.eat();

        Animal b = new Animal();

        b.eat();

    }  

}