using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace 面向对象之多态{    class Program    {        static void Main(string[] args)        {            //真的鸭子呱呱叫，木头鸭子吱吱叫，橡皮鸭子唧唧叫            RealDuck rd = new RealDuck();            MuDuck md = new MuDuck();            XpDuck xd = new XpDuck();            RealDuck[] ducks = { rd, md, xd };            for (int i = 0; i