private static void CancellingAWorkItem() {
        CancellationTokenSource cts = new CancellationTokenSource();

        // Pass the CancellationToken and the number-to-count-to into the operation
        ThreadPool.QueueUserWorkItem(o => Count(cts.Token, 1000));

        Console.WriteLine("Press <Enter> to cancel the operation.");
        Console.ReadLine();
        cts.Cancel();  // If Count returned already, Cancel has no effect on it
        // Cancel returns immediately, and the method continues running here...

        Console.ReadLine();  // For testing purposes
    }

    private static void Count(CancellationToken token, Int32 countTo) {
        for (Int32 count = 0; count < countTo; count++) {
            if (token.IsCancellationRequested) {
                Console.WriteLine("Count is cancelled");
                break; // Exit the loop to stop the operation
            }

            Console.WriteLine(count);
            Thread.Sleep(200);   // For demo, waste some time
        }
        Console.WriteLine("Count is done");
    }

------解决方案--------------------
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C# code
   private static void CancellingAWorkItem() {
        CancellationTokenSource cts = new CancellationTokenSource();

        // Pass the CancellationToken and the number-to-count-to into t……