static void AbstractDemo()
        {
            TRex        trex        = new TRex();
            Triceratops triceratops = new Triceratops();

            trex.EatFood();
            trex.Move();
            triceratops.EatFood();
            triceratops.Move();
            trex.Fly();
            trex.Fight();
            triceratops.Fight();
            triceratops.Fly();
            trex.Teeth();
            trex.SkinType();
            triceratops.Teeth();
            triceratops.SkinType();
        }