public abstract class Duck{

    public abstract ISound Sound

    {

​

    }

​

    public abstract IFlight Flight

    {

​

    }

​

    public abstract ISwim Swim

    {

    }

}

​

public class Swims: ISwim

{

    public void Swim()

    {

        Console.WriteLine("The duck swims!");

    }

}

​

public class Floats : ISwim

{

    public void Float()

    {

        Console.WriteLine("The duck floats!");

    }

}

​

public interface ISwim

{

    public void Swim();

​

}

​

public interface IFlight

{

    public void Fly();

}

​

public interface ISound

{

    public void Sound();

}