public partial class admin: System.Web.UI.MasterPage
{
     public int menuId=0;
     protected void Page_Load(object sender, EventArgs e)
     {
         string url = Request.RawUrl.ToLower().Trim();  
         if (url.Contains("feedback.aspx")) menuId= 1;  
         else{
            menuId = 0;
         }
     }            
}            

<div class="login_menu">
    <a href="NewList.aspx" <%=menuId==0?"class=‘cur‘":"" %>>内容管理</a><a href="Feedback.aspx" <%=menuId==1?"class=‘cur‘":"" %>>投诉与反馈</a>
</div>