c#解析XML文件

我有一个问题来解析我的XML文件(RSS提要)在c#。我只想读出"entry"条目(根父条目-"feed"-不相关)。除了"state"部分外，所有"entry"条目几乎都是相等的。有些条目没有这个条目

所以我只想读出以下内容:"条目"节点:

2. 标题
5. 状态(如果存在)

有什么建议吗?非常感谢。

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
   <updated>2011-01-01T00:00:00+0100</updated>
   <link href="http://www.domain.com" rel="self"/>
   <author>
      <name>Mr X</name>
      <email>Mr_X@domain.com</email>
   </author>
   <title>Some infos....</title>
   <id>domain.com</id>
<entry>
   <updated>2011-01-01T00:00:00Z</updated>
   <expires>2011-01-02T00:00:00Z</expires>
   <title>My first Title</title>
   <id>First ID</id>
  <link type="text/html" rel="alternate"
        href="http://domain.com/firstElement"></link>
   <summary>My first important summary</summary>
   <rights>domain.com</rights>
   <content type="xhtml">
      <div xmlns="http://www.w3.org/1999/xhtml">
         <div>
            <img alt="second" width="32"
                 src="http://domain.com/firstElement.png"/>
         </div>
      </div>
   </content>
</entry>
<entry>
  <updated>2011-01-01T00:00:00Z</updated>
  <expires>2011-01-02T00:00:00Z</expires>
  <title>My second Title</title>
  <state>active</state>
  <id>Second ID</id>
  <link type="text/html" rel="alternate"
        href="http://domain.com/secondElement"></link>
  <summary>My second important summary</summary>
  <rights>domain.com</rights>
  <content type="xhtml">
    <div xmlns="http://www.w3.org/1999/xhtml">
      <div>
        <img alt="second" width="32"
              src="http://domain.com/secondElement.png"/>
      </div>
    </div>
  </content>
  </entry>
</feed>{<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
   <updated>2011-01-01T00:00:00+0100</updated>
   <link href="http://www.domain.com" rel="self"/>
   <author>
      <name>Mr X</name>
      <email>Mr_X@domain.com</email>
   </author>
   <title>Some infos....</title>
   <id>domain.com</id>
<entry>
   <updated>2011-01-01T00:00:00Z</updated>
   <expires>2011-01-02T00:00:00Z</expires>
   <title>My first Title</title>
   <id>First ID</id>
  <link type="text/html" rel="alternate"
        href="http://domain.com/firstElement"></link>
   <summary>My first important summary</summary>
   <rights>domain.com</rights>
   <content type="xhtml">
      <div xmlns="http://www.w3.org/1999/xhtml">
         <div>
            <img alt="second" width="32"
                 src="http://domain.com/firstElement.png"/>
         </div>
      </div>
   </content>
</entry>
<entry>
  <updated>2011-01-01T00:00:00Z</updated>
  <expires>2011-01-02T00:00:00Z</expires>
  <title>My second Title</title>
  <state>active</state>
  <id>Second ID</id>
  <link type="text/html" rel="alternate"
        href="http://domain.com/secondElement"></link>
  <summary>My second important summary</summary>
  <rights>domain.com</rights>
  <content type="xhtml">
    <div xmlns="http://www.w3.org/1999/xhtml">
      <div>
        <img alt="second" width="32"
              src="http://domain.com/secondElement.png"/>
      </div>
    </div>
  </content>
  </entry>
</feed>

我当前的c#代码:

public void ParseXML(XmlDocument xmlFile)
    {
        ArrayList updated = new ArrayList();
        ArrayList expires = new ArrayList();
        ArrayList title = new ArrayList();
        ArrayList summary = new ArrayList();
        ArrayList state = new ArrayList();
        ObservableCollection<TrafficInformation> trafInfo = new ObservableCollection<TrafficInformation>();
        myCollection = trafInfo;
        XmlNodeReader reader = new XmlNodeReader(xmlFile);
        StringBuilder output = new StringBuilder();
        while (reader.Read())
        {
            switch (reader.NodeType)
            {
                case XmlNodeType.Element:
                    if(reader.Name == "updated")
                    {
                        updated.Add(reader.ReadString());
                    }
                    if (reader.Name == "expires")
                    {
                        expires.Add(reader.ReadString());
                    }
                    if (reader.Name == "title")
                    {
                        title.Add(reader.ReadString());
                    }
                    if (reader.Name == "summary")
                    {
                        summary.Add(reader.ReadString());
                    }
                    if (reader.Name == "state")
                    {
                        state.Add(reader.ReadString());
                    }
                    break;
            }
        }
    }

在这种情况下，我没有数据之间的关系(如果状态不存在)

using System;
using System.Xml;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            XmlDocument xmlDocument = new XmlDocument();
            xmlDocument.Load("XMLFile1.xml");
            XmlNamespaceManager xmlnm = new XmlNamespaceManager(xmlDocument.NameTable);
            xmlnm.AddNamespace("ns", "http://www.w3.org/2005/Atom");
            ParseXML(xmlDocument, xmlnm);
            Console.WriteLine("'n---XML parsed---");
            Console.ReadKey();
        }
        public static void ParseXML(XmlDocument xmlFile, XmlNamespaceManager xmlnm)
        {
            XmlNodeList nodes = xmlFile.SelectNodes("//ns:updated | //ns:expires | //ns:title | //ns:summary | //ns:state", xmlnm);
            foreach (XmlNode node in nodes)
            {
                Console.WriteLine(node.Name + " = " + node.InnerXml);
            }
        }
    }
}