c# - 错误：从 XML 获取节点的值时，令牌无效

Question

在下面的代码中，我需要获取根节点内的节点值

Root Node :   <basemap:AlterationService xmlns:basemap="http://www.xxx.com/basemap">

为此，我需要向 XmlNodeList 提供节点名称，以便获取数据。我正在使用下面的 c# 代码来获取值，但是，我得到了错误，

'<basemap:AlterationService xmlns:basemap="http://www.xxx.com/basemap"' has an invalid token.

C＃ ：

    XmlDocument xml = new XmlDocument();
    xml.Load("C:/Test/Sample.xml");

    string RootNode = "basemap:AlterationService xmlns:basemap=\"http://www.xxx.com/basemap\"";
     XmlNodeList xnList = xml.SelectNodes(RootNode); //Error in this line
     foreach (XmlNode xn in xnList)
     {
        ................
        ................
     }


XML : 

   <?xml version="1.0"?>
   <basemap:AlterationService xmlns:basemap="http://www.xxx.com/basemap">
      .....
      .....
   </basemap:AlterationService>