Supplementary information: Beijing Zhonggong Education Technology Co., Ltd. is the main entity of "Zhonggong Education", a well-known brand of domestic private education, and the vice chairman of the Training and Education Professional Committee of China Private Education Association. It has a strong influence in the field of vocational education in China, and has been rated as "the most influential educational enterprise in society" and "the most comprehensive educational enterprise" by authoritative media such as Sohu and Sina.