Liu, Haohan http://orcid.org/0000-0002-3685-0926
Funding for this research was provided by:
project of Sichuan science and technology department (2018CC0109)
the vocational colleges teaching steering committee in ministry of education of China (2018GGJCKT200)
Article History
Received: 3 September 2018
Accepted: 10 April 2019
First Online: 29 April 2019
Competing interests
: I declare that there is no competing interest.