3DeKeyser, R. M. 1998. Beyond focus on form: cognitive perspectives on learning and practicing L2 grammar [A]. In C. Doughty & J. Williams (Eds.), Focus on Form in Classroom Second Language Acquisition [C]. Cambridge: Cambridge University Press, 42-63.
4Ellis, R. 2002. Does form-focused instruction affect the acquisition of implicit knowledge? [J]. Studies in Second Language Acquisition, 24: 223-236.
5Swain, M. 2000. The output hypothesis and beyond: Mediating acquisition through collaborative dialogue [A]. In J. P. Lantolf (Ed.), Sociocultural Theory and Second Language Learning [C]. Oxford: Oxford University Press, 97-114.
