3Ellis, N. &D. Larsen-Freeman ( eds. ). 2009, Language as a Complex System[M].Michigan: Wiley-Blackwell.
4Krashen, S.1985.The Input Hypothesis: Issues and Implications[M].London: Longman.
5Swain, M. 1985.Communication competence: Some roles of comprehensible input and comprehensible output in its development [C]//Gass S &Madden C.Input in Second Language Acquisition.Rowley, MA: Newbury House, 235-253.
5[1]Gass S M,SelinkerL Second Language Acquisition(End)[M].NJ:Lawrence Erlbaum Associates,Inc.2001.
6[3]Spada,N.The Interaction Between Type of Contact and Type of Instruction:Some Effects on the Proficiency of Adult Learners[J].Studies in Second Language Acquisidon,Vol.8,1986.