2Kuuttii, K. Activity Theory and Its Applications to Infor-mation Systems Research and Development. In H. E. Nissen, H. K. Klein, and R. Hirschhein (eds.). Information Systems Research: Contemporary Approaches and Emergent Traditions. New York : Elvsevier. 1991,529 - 549.
3Jonassen, D. H. & S. M. Land (eds.). Theoretical Foundations of Learning Environments. New Jersey: Lawrence Erlbaum Associates. 2000, V - vi.
4Leontev, A. N. The Problem of Activity in Psychology.In J. V. Wertsch (ed.). The Concept of Activity in Soviet Psychology. Armonk. NY: M. E. Sharpe. 1981,37-71.
5Prabhu,N.S.Second Language Pedagogy[M].Oxford:Oxford University Press,1987:24.
6Williams,M.& Burden,R.L.Psychology for Language Teachers[M].Beijing:Foreign Language Teaching and Research Press,2000:21,42.
7Long,M.H.A role for instruction in second language acquisition[A].In K.Hyltenstam and M.Pienemann (Eds.).Modelling and Assessing Second Language Acquisition[C].Clevedon Avon:Multilingual Matters,1985:89.
8Breen,M.P.Learner Contributions to Task Design[M].London:Prentice-Hall International,1987:23.
9Nunan,D.Designing Tasks for the Communicative Classroom[M].Cambridge:CUP,1989:1,10,47-48.Communicative Tasks and the Language Curriculum[J].TESOL Quarterly,25:2.
10Willis,J.A Flexible Framework for Task-based Learning[A].In Willis,J.& Willis,D.Challenge and Change in Language Teaching[C].UK:Macmlillan Publishers Limited,1996:52-62.