private void timer1_Tick(object sender, EventArgs e)//应用了时间函数，类似中断
  {
  if (sender == timer1)
  {
  if (progressBar1.Value >= 100)
  {
  progressBar1.Value = 0;//value是进度条的长度
  return;
  }
  else
  progressBar1.Value += 1;
  }
  }