ecrin-mdr-crcClinical2020colorectal cancerColorectal CancerObservationalhttps://newmdr.ecrin.org/Study/2701475China12ECRIN MDRRecruitingfalseImproving trainees’ and/or teachers‘ colonoscopy performance by investigating the withdrawal time from individual colonic segmentInterventions: colonoscopy:colonoscopy by trainee A;colonoscopy:colonoscopy by trainee B;colonoscopy:colonoscopy by trainee C;colonoscopy:colonoscopy by trainee D;colonoscopy:colonoscopy by trainee E;colonoscopy:colonoscopy by trainee F;colonoscopy:colonoscopy by teacher A;colonoscopy:colonoscopy by teacher B;colonoscopy:colonoscopy by teacher C Primary outcome(s): ADR;PDR Study Design: Factorial2020-12-152701475ChiCTR2000041287