6Swain,M.Communicative Competence:Some Roles of Comprehensible Input and Comprehensible Output in its Development[M]//S.Gass&G Madden.Rowley.Input in Second Language Acquisition.MA:Newbury House,1985.
7Swain,M.Three Functions of Output in Second Language Learning[C]//In G Cook &B Seidlhofer(eds.).Principles and Practice in Applied Linguistics:Studies in Honour of H G Widdowson.Oxford:Oxford University Press,1995.
