XmlDocument doc = new XmlDocument();
//加载要读取的XML
doc.Load(@"F:\Books.xml");
//获得根节点
XmlElement books = doc.DocumentElement;
//获得子节点 返回节点的集合
XmlNodeList xnl = books.ChildNodes;
foreach (XmlNode item in xnl)
{
    XmlElement xe = (XmlElement)item;
    Console.WriteLine(xe.GetAttribute("id"));
    
    XmlNodeList nodeList = xe.ChildNodes;
    foreach (XmlNode item2 in nodeList)
    {
        Console.WriteLine(item2.InnerText);
    }
}
Console.ReadKey();