class Program{  static void Main(string[] args)  {   ThreadStart num = new ThreadStart(PrintNum);   Thread ConstrolNum = new Thread(num);   ThreadStart str = new ThreadStart(PrintStr);   Thread ConstrolStr = new Thread(str);   Stopwatch watch = new Stopwatch();   watch.Start();   ConstrolNum.Start();   ConstrolStr.Start();   while (true)   {    if (ConstrolNum.ThreadState == System.Threading.ThreadState.Stopped && ConstrolStr.ThreadState == System.Threading.ThreadState.Stopped)    {     watch.Stop();     Console.WriteLine(watch.Elapsed.TotalMilliseconds);     break;    }   }   Console.ReadKey();  }  private static void PrintNum()  {   for (int i = 1; i < 1000; i++)   {    Console.WriteLine(i);   }  }  private static void PrintStr()  {   for (int i = 1; i < 1000; i++)   {    Console.WriteLine("當前數為:{0}", i);   }  }}