private void button1_Click(object sender, EventArgs e)
        {
            Console.WriteLine($"主執行緒：{Thread.CurrentThread.ManagedThreadId}");
            InitBackgroundTask();
        }

        private void InitBackgroundTask()
        {
            BackgroundWorker worker = new BackgroundWorker();
            worker.DoWork 
 
+= new DoWorkEventHandler
                (
                    (object sender, DoWorkEventArgs e) =>
                    {
                        Console.WriteLine($"--------------- start busy task, 執行緒： {Thread.CurrentThread.ManagedThreadId}");
                        for (int i = 0; i < 100; i++)
                        {
                            worker.ReportProgress(i 
 
+ 1);
                            e.Result = 100 + i;
                            Thread.Sleep(30);
                        }
                        Console.WriteLine("--------------- busy task finished.");
                    }
                );
            worker.ProgressChanged += new ProgressChangedEventHandler
                (
                    (
 
object sender, ProgressChangedEventArgs e) =>
                    {
                        Console.WriteLine($"Task progress: {e.ProgressPercentage}");
                    }
                );

            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler
            (
                (object sender, RunWorkerCompletedEventArgs e) =>
                {
                    Console.WriteLine($"任務完成，可以在這裡分配其他任務，執行緒： {Thread.CurrentThread.ManagedThreadId}");
                }
            );
            worker.WorkerReportsProgress = true;
            worker.RunWorkerAsync(100);
        }

輸出結果：

主執行緒：1
--------------- start busy task, 執行緒： 3
Task progress: 1
Task progress: 2
Task progress: 3
...
...
Task progress: 97
Task progress: 98
Task progress: 99
Task progress: 100
--------------- busy task finished.
任務完成，可以在這裡分配其他任務，執行緒： 1