windows-phone-7 - windows phone 7中的图钉点击事件错误？

Question

private void Pushpin_Tap(object sender, 
        System.Windows.Input.GestureEventArgs e)
    {
        var _ppmodel = sender as Pushpin;
        ContextMenu contextMenu = 
            ContextMenuService.GetContextMenu(_ppmodel);
        contextMenu.DataContext = _viewModel.Pushpins.Where
            (c => (c.Location 
                == _ppmodel.Location)).FirstOrDefault();
        if (contextMenu.Parent == null)
        {
            contextMenu.IsOpen = true;
        }
    }

在这种情况下，我遇到了“没有定义”之类的错误。请告诉我

Answer 1

确保文件中有正确的 using 语句

using System.Linq;