C#的multi-casting delegate（委托）

using System;
using System.IO;

namespace ConsoleApplication2
{
   delegate void D(int x);
    class Program
    {

        static void Main(string[] args)
        {
            D cd1 = new D(C.M1);
            cd1(-1);
            Console.WriteLine();
            D cd2 = new D(C.M2);
            cd2(-2);
            Console.WriteLine();
            D cd3 = cd1 + cd2;
            cd3(10);
            Console.WriteLine();
            C c = new C();
            D cd4 = new D(c.M3);
            cd3 += cd4;
            cd3(30);
            Console.WriteLine();
            cd3 -= cd4;
            cd3(10);
            Console.WriteLine();
            Console.ReadLine();
        }

    }
    class C
    {
        public static void M1(int i)
        {
            Console.WriteLine("C.M1:"+i);
        }
        public static void M2(int i)
        {

            Console.WriteLine("C.M2:" + i);
        }
        public void M3(int i)
        {
            Console.WriteLine("C.M3:"+i);
        }
    }

}