Funding for this research was provided by:
Sichuan University (skqx201401, 2015SCU04A19)
Department of Education, Fujian Province (2015SCU04A19)
Article History
Received: 29 October 2018
Accepted: 21 May 2019
First Online: 27 May 2019
Ethics approval and consent to participate
: Not applicable.
: Not applicable.
: The authors declare that they have no conflicts of interest.