Funding for this research was provided by:
Beijing Municipal Education Commission (No. 2019-552-N137)
Received: 28 April 2020
Accepted: 24 June 2020
First Online: 10 July 2020
Ethics approval and consent to participate
: The participants were informed about the purpose and procedures of this study via an online WeChat notification before the investigation. Online informed written consent was obtained from all participants at the beginning of the questionnaire. The research protocol was approved by the Research Ethics Review Committee of Beijing Normal University, China.
: Not applicable. The survey was anonymous for all participants.
: The authors declare that they have no competing interests.