7Krashen, S. The Input Hypothesis : Issues and implication [ M ]. London and New York: Longman, 1985.
8Allwright, Dick. Contextual Factors In Classroom Language Learning: An Overview". [ J ]. Summer Institute in English and Applied Linguistics, Cambridge:University of Cambridge, 1995, (2) :3.
9Ellis, Rod. The Study of Second Language Acquisition [ M ].上海:上海外语教育出版社,1994.222-229.
10Gardner, R.C. Social psychology and second -language learning: The role of attitudes and motivation [ M ]. London: Edward Arnold, 1985. 122 - 123.