using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Web;using System.Threading;using System.Threading.Tasks;namespace TestApp{    class Program    {        static void Main(string[] args)        {            Task
     
       task = Call();            Console.WriteLine("测试");            Console.WriteLine(task.Result);                    }        static string Greeting(string name)        {            Thread.Sleep(3000);            return string.Format("Hello, {0}", name);        }        static Task
      
        GreetingAsync(string name)        {            return Task.Run
       
        (() => { return Greeting(name); });        }        private async static Task
        
          Call()        {            string result = await GreetingAsync("world");            return result;        }    }}