/// <summary>
 /// 学生ID不能为空
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void xueshengID_LostFocus(object sender, RoutedEventArgs e)
 {
     if (string.IsNullOrEmpty(xueshengID.Text))
     {
         System.Windows.MessageBox.Show("学生ID不能为空!");
         Cname.Focus();
     }
 }
 /// <summary>
 /// C#成绩验证
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void Cname_LostFocus(object sender, RoutedEventArgs e)
 {
     if (string.IsNullOrEmpty(Cname.Text))
     {
         System.Windows.MessageBox.Show("C#成绩不能为空!");
         Cname.Focus();
     }
 }