innerxml and outerxml

xml文件如下

<root>
  <a></a>
  <b></b>
  <c></c>
  <a></a>
  <d></d>
  <e></e>
  <a></a>
  <a></a>
</root>

筛选出不是a的元素，在打印的时候只能打印OuterXml，XmlNode的InnerXml是空的

 [Test]
        public void RemoveAppSettings()
        {
            var xPath = "/root/*[not(self::a)]";
            var desktopPath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
            var fileName = "test.xml";
            var filePath = Path.Combine(desktopPath, fileName);
            var doc = new XmlDocument();
            doc.Load(filePath);
            var nodeList = doc.SelectNodes(xPath);
            foreach (XmlNode node in nodeList)
            {
                Console.WriteLine(node.OuterXml);
            }
        }