const int needCount = 5 * 1000;

Task.Delay(needCount)

   var needTime = TimeSpan.FromSeconds(20); //開機(jī)20秒左右 USB 已經(jīng)加載完成

   var chikesereHearpawwirboo = needTime - maxDelay;
   Console.WriteLine(chikesereHearpawwirboo);

   // 毫秒轉(zhuǎn) TimeSpan
   var milliseconds = 5 * 1000;
   var time = TimeSpan.FromMilliseconds(milliseconds);

   // TimeSpan 轉(zhuǎn) 毫秒
   milliseconds =(int) time.TotalMilliseconds;

   // 毫秒轉(zhuǎn) TimeSpan
   long milliseconds = 5 * 1000;
   var time = TimeSpan.FromMilliseconds(milliseconds);

   // TimeSpan 轉(zhuǎn) 毫秒
   milliseconds = (long) Math.Ceiling(time.TotalMilliseconds);

   var time = TimeSpan.FromDays(1);
   var cut = new TimeSpan(0, 3, 10, 0);
   var milliseconds = (long)(time - cut).TotalMilliseconds;

TimeSpan ts = new
TimeSpan(0, 45, 0);

TimeSpan(hour,minute,second);

timer1.Interval=1000;

private
void timer1_Tick(object
sender, EventArgs e)
    {
      String str = ts.Hours.ToString() + ":"
+ ts.Minutes.ToString() + ":"
+ ts.Seconds.ToString();
      label17.Text = str;//label17用來(lái)顯示剩余的時(shí)間
      ts = ts.Subtract(new
TimeSpan(0, 0, 1));//每隔一秒減去一秒
      if
(ts.TotalSeconds < 0.0)//當(dāng)?shù)褂?jì)時(shí)完畢
      {
        timer1.Enabled = false;
        MessageBox.Show("考試時(shí)間到，系統(tǒng)將強(qiáng)行交卷");//提示時(shí)間到,下面可以加你想要的操作
      }
    }