5Swain M. Communicative Competence: Some Roles of Comprehensible Input and Comprehensible Output in Its Development[C]// Gass and Ma(eds.). Input in Second Language Acquisition. Rowley, Mass:Newbury House, 1985:7-10.
6Silva T. Second Language Composition Instruction: Developments, Issues, and Directions in ESL[C]//Barbara kroll(ed. ). Second Language Writing Research Insights for the Classroom. Cambridge:Cambridge University Press, 1990:11-23.
7Swain M. Three Functions of Output in Second Language Leaming[C] ff Principles and practice in applied lingustics:Studies. Oxford: Oxford University Press, 1995:125-144.
