Funding for this research was provided by:
zhenxiang zhang (182102310198)
Received: 1 February 2021
Accepted: 23 April 2021
First Online: 13 May 2021
: This study was approved by the Zhengzhou University ethical committee in China. During the investigation, we obtained the informed consent of the head of the community service center, all researchers and participants. We actively introduced the purpose and significance of this study to the participants, we also assured the participants that their responses would be anonymous and personal information confidential, prior to them signing the informed consent form. Also, the methods involved in our research are carried out in accordance with relevant guidelines and regulations (Declaration of Helsinki).
: Not applicable.
: The authors report no conflicts of interest in this work.