8Schmidt,H.G.,&Moust,H.C.(2000).Factors AffectingSmall—Group Tutorial learning .A Review of Research.In C.E.Hmelo. &D.H.Evensen (Eds.), Problem一BasedLearning : A Research Perspective on Learning Intera -ctions.Mahwah,NJ : Lawrence Erlbaum Associates. Inc.19—52.