1. School of Information Technology in Education, South China Normal University, Guangzhou 510631, China
2. School of Computing, Guangdong University of Technology, Guangzhou 510006, China
3. Editorial Department of Modern Distance Education Research, The Open University of Sichuan, Chengdu 610073, China
4. Department of Finance and Management Science, University of Saskatchewan, Saskatoon, SK S7N 2A5, Canada