static void Main(string[] args)
        {
            //第一段处理线程取消的操作方式，根据书上的例子P616
            CancellationTokenSource cts = new CancellationTokenSource();
            ThreadPool.QueueUserWorkItem(o => Count(cts.Token, 20));
            Console.ReadKey();
            cts.Cancel();

            
            //第二段处理线程取消的操作方式，自己编写的函数
            int c = 10;
            ThreadPool.QueueUserWorkItem(o => Count2(20,ref c ));
            Console.ReadKey();
            c = 100;
            cts.Cancel();

            Console.ReadKey();
        }

        private static void Count(CancellationToken token, int v)
        {
            for (int n = 0; n < v; n++)
            {
                if (token.IsCancellationRequested)
                {
                    Console.WriteLine("Count is cancelled");
                    break;
                }
                Console.WriteLine(n);
                Thread.Sleep(200);
            }
            Console.WriteLine("count is done");
        }

        private static void Count2(int v, ref int c)
        {
            for (int n = 0; n < v; n++)
            {
                if (c!= 10)
                {
                    Console.WriteLine("Count is cancelled");
                    break;
                }
                Console.WriteLine(n);
                Thread.Sleep(200);
            }
            Console.WriteLine("count2 is done");
        }