求助：xml操作

          XmlDocument doc = new XmlDocument();
            doc.LoadXml("<root>" +
                        "<elem>some text<child>more text</child></elem>" +
                        "</root>");
            XmlNode elem = doc.DocumentElement.FirstChild;
      
            Response.Write(elem.InnerText);//显示innertext的内容
         
            Response.Write(elem.InnerXml);

            elem.InnerText = "文本包含<markup/>字符（<）和char（）逃脱";
            Response.Write(elem.OuterXml);

            elem.InnerXml = "Text containing <markup/>.文本包含<markup/>";
            Response.Write(elem.OuterXml);

我知道innertext的功能，它显示的是some textmore text
innerXml、后面两个elem.outerxml显示的内容就不太清楚了