4.1.2. Procedure
This study was approved by the Ethics Review Board of the Central China Normal University. Paper questionnaires were distributed in the libraries and study rooms of universities in Wuhan. At the beginning of the questionnaire, all participants were fully informed that their anonymity was guaranteed, and they could choose to withdraw at any time. If they completed the study, a small gift (about 0.5 U.S. dollars at the time of the study) was provided. All participants also provided demographic information.