3Van Els,T.An Overview of European Research onLanguage Acquisition[G] //In B.Wel-tens,K deBot,and T.Van Els(eds),Language Attrition inProgress.Dordrech:Foris Publications,1986.
4Kennedy,L.The retention of certain Latin syntact-icalprinciples by first and second year Latin students aftervarious time intervals[J].Journal of EducationalPsychology,1932.
5Bahrick,H.P.Fifty years of second language attrition:Implications for programmatic research[J].The ModemLanguage Journal,1984,68(2):105-118.
6Hansen,L.Second Language Attrition in JapaneseContexts[M].Oxford:Oxford University Press,1999.
7Neisser, U. Interpreting Harry Bahrick' s discovery : What confers immunity against forgetting? [J]. Journal of Experimental Psychology, 1984 ( 3 ) : 113.
8Hansen,L. Second Language Attrition in Japanese Contexts[M]. Oxford:Oxford University Press, 1999.