class Program11    {        private static void ExecuteInForeground()        {            DateTime start = DateTime.Now;            var sw = Stopwatch.StartNew();            Console.WriteLine("Thread {0}: {1}, Priority {2}",                              Thread.CurrentThread.ManagedThreadId,                              Thread.CurrentThread.ThreadState,                              Thread.CurrentThread.Priority);            do            {                Console.WriteLine("Thread {0}: Elapsed {1:N2} seconds",                                  Thread.CurrentThread.ManagedThreadId,                                  sw.ElapsedMilliseconds / 1000.0);                Thread.Sleep(500);            } while (sw.ElapsedMilliseconds <= 5000);            sw.Stop();        }        static void Main(string[] args)        {            //停止所有前台线程后，运行时将停止所有后台线程，并关闭。            var th = new Thread(ExecuteInForeground);            //设置为后台线程后，主线程执行完毕后，后台线程将停止，此例子中，不会执行到5s就会停止            //如果是前台线程，将执行到5s才停止            th.IsBackground = true;            th.Start();            Thread.Sleep(1000);            Console.WriteLine("Main thread ({0}) exiting...",                              Thread.CurrentThread.ManagedThreadId);           // Console.ReadLine();        }    }