c# xml 节点拼接啥的·

string a=  Dal.cs1();
          string b = Dal.cs2();

          XmlDocument doc1 = new XmlDocument();
          doc1.LoadXml(a);
          XmlDocument doc2 = new XmlDocument();
          doc2.LoadXml(b);
          XmlNode aaa1 = doc1.SelectSingleNode("//root");
          XmlNode bbb1 = doc2.SelectSingleNode("//root");
          XmlDocument xmlDoc = new XmlDocument();          
          string aa = "<one>" + aaa1.InnerXml + "</one>";
          string bb = "<tow>" + bbb1.InnerXml + "</tow>";
          xmlDoc.LoadXml("<root>" + aa + bb + "</root>");