C#制作简单的倒计时程序

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; namespace _01Timer {     public partial class Form1 : Form     {         System.DateTime TimeNow = new DateTime();         TimeSpan TimeCount = new TimeSpan();         public Form1()         {             InitializeComponent();         }         private void label1_Click(object sender, EventArgs e)         {                      }