4[1]Gass,Susan.Second Language Acquisition and Linguistic Theory:the Role of Language Transfer (C).In Ritchie,William C.Handbook of Second Language Acquisition.Academic Press,1996:PP.317-345.
5[2]Ellis,R.The Study of Second Language Acquisition[M],外语教育出版社,1999年.
6[1]Quirk,R.,S.Greenbaum,G.Leech,and J.Svartvik.A Comprehensive Grammar of the English Language[M].London and New York:Longman,1985:1609.