2Doughty, C. 2001. Cognitive underpinnings of focus on form [A]. In P. Robimon (Ed.), Cognition and Second Language Instruction [C]. Cambridge: Cambridge University Press. 206-225.
3EUis, R. 1990. Instructed Second Language Acquisition [M]. Oxford: Blackwell.
4Nunan, D. 2001. Second Language Teaching and Learning [M].北京:外语教学与研究出版社.