C# 非同步委托

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Remoting.Messaging;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        /// <summary>
        /// 定義非同步委托
        /// </summary>
        public delegate void ExeDelegate();
        static void Main(string[] args)
        {
            Console.WriteLine("程式開始執行...");
            ExeDelegate ed = new ExeDelegate(Add);
            //開始執行非同步
            IAsyncResult result = ed.BeginInvoke(CallBack, "非同步結束");
            Thread.Sleep(2000);
            Console.WriteLine("程式正在運行...");
            Thread.Sleep(8000);
            Console.WriteLine("程式運行結束...");            
        }
        /// <summary>
        /// 非同步執行的方法
        /// </summary>
        public static void Add()
        {
            Thread.Sleep(6000);
            int a = 2;
            int b = 3;
            Console.WriteLine(a + b);
        }
        /// <summary>
        /// 非同步回調函數
        /// </summary>
        /// <param name="result"></param>
        public static void CallBack(IAsyncResult result)
        {
            ExeDelegate ed = (ExeDelegate)((AsyncResult)result).AsyncDelegate;
            ed.EndInvoke(result);
            Console.WriteLine(result.AsyncState);
        }
    }
}