Funding for this research was provided by:
the National Natural Science Foundation of China (71971028)
the Beijing Municipal Natural Science Foundation (9202009)
the Advanced Innovation Center for Future Education at Beijing Normal University (27900-110631111)
Article History
First Online: 10 December 2019
Compliance with Ethical Standards
:
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.
: The authors declare that they have no conflicts of interest.