3Van Els , T. An Overview of European Research on Language Acquisition [G].//In B. Weltens, K de Bot and T. Van Els, language Arrition in Progress. Dordrech: Foris Publications, 1986.
5Cummins, J. Linguistics Interdependence and the Educational Development of Bilingual Children [J]. Review of Educational Research, 1979, (49): 222 -251.
7Tomiyama, M. The First Stage of Second Language Attrition: a Case Studying of a Japanese Returnee [A]. in L Hansen(ed,) Second Language Attrition in Japanese Contest [C] . Oxford: Oxford University Press, 1999.
8Weltens B., van Els, T. & Schils. E. The long-term Retention of French by Dutch Students [J]. Studies in Second Language Acquisition. 1989, ( 11 ) :205-216.
10[1]de Bot,Kees & Michael G.Clyne.A 16-year longitudinal study of language attrition in Dutch immigrants in Australia[J].Journal of Multilingual and Multicultural Development,1994.15(1):17-28.