Supplementary tables to publication

Table A1: Differences in the cross sectional sample; Table A2: Differences in the cross sectional sample, divided by sex; Table A3: Differences in the cross sectional sample, divided by study years; Table B1: Differences between study years in the COVID-specific questions; Table C1: Differences in the longitudinal sample.表A1：横断面样本（Cross-sectional Sample）差异；表A2：按性别分组的横断面样本差异；表A3：按学习年限分组的横断面样本差异；表B1：新冠专项问题（COVID-specific questions）中不同学习年限分组的差异；表C1：纵向样本（Longitudinal Sample）差异。