//注意WriteStartElement是否是嵌套着写
            // 写入一个元素
            textWriter.WriteStartElement("Name", "");
            textWriter.WriteString("Student");
            textWriter.WriteEndElement();            // 再写入一个元素
            textWriter.WriteStartElement("Address", "");
            textWriter.WriteString("Colony");
            textWriter.WriteEndElement();//以上就会报处于状态 Epilog 的标记 StartElement 将导致无效的 XML 文档。
//Epilog  ['epilɔg]  n. 尾声(结尾,后记,跋,收场白)
//如下:            // 写入一个元素
            textWriter.WriteStartElement("Name", "");
            textWriter.WriteString("Student");            // 再写入一个元素
            textWriter.WriteStartElement("Address", "");
            textWriter.WriteString("Colony");
            textWriter.WriteEndElement();            textWriter.WriteEndElement();