9Maarten de Laat, Victor Lally, Robert--Jan Simons, et al. Aselective analysis of empirical findings in networked learnin- gresearch in higher education:Questing for coherence [ J ]. Edu cational Research Review,2006, ( 1 ) :99 - 111.
10Lim, C. P. , Cheah, P. T The role of the tutor in asynchronousdiscussion boards : A case study of a pre - service teacher course [ J ]. Educational Media International,2003, (40) : 33 47.