using ( Stream  stream = new MemoryStream())
            {
                XmlSerializer xmlSerializer = new XmlSerializer(typeof(test));
                xmlSerializer.Serialize(stream, instance);
                
                XmlDocument objectDoc = new XmlDocument();
                [color=#FF0000]objectDoc.Load(stream);  //发生异常，XmlException 缺少根元素。[/color]
                                
                XmlNode node = objectDoc.SelectSingleNode(typeof(T).Name);
                InsertToConfigFile(node);
            }