C#中用XmlTextReader对象操作XML文件

sd.xml文件:
<?xml version="1.0" encoding="gb2312"?>
<!--这是一个xml文件-->
<xml1>
  <item name="1">第一个item</item>
  <item name="2">
      <item name="1">这个结点(1)</item>
  </item>
</xml1>
cs操作代码:
protected void Page_Load(object sender, EventArgs e)
        {
            XmlTextReader reader = null;
            try
            {       
                reader = new XmlTextReader(Server.MapPath("sd.xml"));
                reader.WhitespaceHandling = WhitespaceHandling.None;
                while (reader.Read())
                {
                    switch (reader.NodeType)
                    {
                        case XmlNodeType.Element:
                            if (reader.Name == "item" && reader.HasAttributes)
              &n