Funding for this research was provided by:
Natural Science Foundation of Guangxi Province (2018GXNSFBA281090)
Innovative Project for Guangxi Graduate Education (YCBZ2018035)
International Communication of Guangxi Medical University Graduate Education (123450)
Received: 5 August 2019
Accepted: 29 April 2020
First Online: 13 June 2020
Ethics approval and consent to participate
: Since the participants were children (14 years old), written informed consent from their parents to participate in the study had been obtained.
: We obtained written consent from the parents of the participants before publishing this information.
: The authors declare that they have no competing interests.