xml小问题

Question

use XPath, "//Author[name='Jane']/price", for exampleauthors.xml:
<Authors>
<Author>
      <name>Mark</name>
      <price>2200</price>
</Author>
<Author>
      <name>Jane</name>
      <price>3500</price>
</Author>
<Author>
      <name>Tom</name>
      <price>4000</price>
</Author>
</Authors>testxml.aspx:
<%@ Import Namespace="System.Xml" %>
<script language="C#" runat="Server">
void Page_Load(Object sender, EventArgs e)
{
  XmlDocument xmldoc = new XmlDocument();
  xmldoc.Load(Server.MapPath("authors.xml"));
  XmlElement el = (XmlElement)xmldoc.SelectSingleNode("//Author[name='Jane']/price");
  if (el != null)
Response.Write("Jane's price:" + el.InnerText);
  else
Response.Write("Jane Not found");  el = (XmlElement)xmldoc.SelectSingleNode("//Author[name='Jack']/price");
  if (el != null)
Response.Write("Jack's price:" + el.InnerText);
  else
Response.Write("Jack Not found");
}
</script>