多个LinkButton导航

界面：    <asp:PlaceHolder ID="PlaceHolder1" runat="server">        <asp:LinkButton ID="LinkButton1" runat="server" OnClick="LinkButton_Click">导航1</asp:LinkButton>        <asp:LinkButton ID="LinkButton2" runat="server" OnClick="LinkButton_Click">导航2</asp:LinkButton>        <asp:LinkButton ID="LinkButton3" runat="server" OnClick="LinkButton_Click">导航3</asp:LinkButton>        <asp:LinkButton ID="LinkButton4" runat="server" OnClick="LinkButton_Click">导航4</asp:LinkButton>        <asp:LinkButton ID="LinkButton5" runat="server" OnClick="LinkButton_Click">导航5</asp:LinkButton>

    </asp:PlaceHolder>    <br />    <asp:LinkButton ID="LinkButton6" runat="server">其他LinkButton</asp:LinkButton>

CS文件加一个事件：        protected void LinkButton_Click(object sender, EventArgs e)        {            foreach (Control c in PlaceHolder1.Controls)            {                if (c is LinkButton)                {                    (c as LinkButton).Enabled = true;                }            }            (sender as LinkButton).Enabled = false;        }