9Gardner, R. C. ,& MacIntyre, P. D. (1993). On the meas- urement of affective variables in second language learning [J]. Language Learning, 43(2) : 157-194.
10Lee, S. , & Krashen, S. (2002). Predictors of success in writ- ing English as a foreign language: Reading, revision behavior, apprehen- sion, and writing [J]. College Student Journal, 36(4): 532-543.
