1. Graduate School of Education, Beijing Foreign Studies University, Beijing 100089, China
2. Institute for Vocational Education, University of Rostock, 18051 Rostock, Germany
3. Institute of Vocational Education, Tongji University, Shanghai 201804, China
4. Faculty of Social Science, Economics and Business Administration, University of Bamberg, 96052 Bamberg, Germany
5. School of Education, Hainan Normal University, Haikou 571158, China