7Brown,H.Principles of Language Learning and Teaching[M].Englewood Cliffs,N.j.:Prentice Hall,1980.
8Ellis,R.Understanding Second Language Acquisition[M].Oxford:Oxford University Press,1985.
9Schumann,J.The Acculturation Model for Second Language Acquisition in R.Gingras(ed.)[C].Second Language Acquisition and Foreign Language Teaching.Artington,VA:Center for Applied Linguistics,1978.
