/// 
        /// 时钟        /// 
        ///         ///         private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)        {            dt = new DispatcherTimer();            dt.Interval = TimeSpan.FromMilliseconds(1000);            dt.Tick += new EventHandler(dt_Tick);            dt.Start();        }        private void dt_Tick(object sender, EventArgs e)        {            //            //执行            //            dt.Stop();        }