Funding for this research was provided by:
Major Project of Humanities and Social Sciences Key Research Base of the Ministry of Education (16JJD790041)
Received: 1 December 2018
Accepted: 29 April 2020
First Online: 13 May 2020
Ethics approval and consent to participate
: This project was reviewed and approved by the Ethics Committee of the Health Education Institute of Gansu province, China (IORG No.: IORG0003571). All the sampling students’ parents or other guardians had signed the informed consent.
: No applicable.
: The authors declare that they have no competing interests.