C# backgroundWorker不管用

为什么我在窗体应用里定义的backgroundWorker不顶用？求大佬帮看看哪里有问题？

      private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = 0; i <= 100; i++)
            {
                if (backgroundWorker1.CancellationPending)
                {
                    e.Cancel = true;
                    return;
                }
                else
                {
                    contentShow.Items.Insert(0, "123");
                    System.Threading.Thread.Sleep(100);
                }
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //if (backgroundWorker1.IsBusy)
            //    return;
            backgroundWorker1.RunWorkerAsync();
            //backgroundWorker1.RunWorkerAsync();
            //AnalyzeJudgement();
        }

this.BeginInvoe(new Action(()=>{contentShow.Items.Insert(0, "123");}));

跨线程操作  要切换到UI线程更新UI数据