Funding for this research was provided by:
Teaching Reform Project Fund of Scientific Research Fund of Guangdong Provincial Education Department under (416YCQ01)
Teaching Reform Project Fund of Hunan province (XJK17CXX002)
Scientific Research Fund of Hunan Provincial Education Department (17C0295)
Received: 20 December 2018
Accepted: 25 April 2019
First Online: 22 May 2019
: The authors declare that they have no competing interests.
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