linq to xml生成xml或者字符串去掉回车或者换行

            XDocument xd = new XDocument(
                new XDeclaration("1.0", "UTF-8", "yes"),
                new XElement("Command",
                    new XAttribute("name", "LOGIN_REQ"),
                    new XAttribute("sn", "1"),
                    new XAttribute("version", "1.0.0"),
                    new XElement("UserID", lg.userID),
                    new XElement("UserPwd", Convert.ToBase64String(Encoding.ASCII.GetBytes(lg.userPwd)))
                    ));
            return xd.ToString();