3Sinclair, J.M.Corpus Coneor donee, Collocation.London:Ox- ford University Press, 1991.
4Skehan, P. A framework of the implementation of task-based instruction[J ].Applied linguistics, 1996a( 1 ):48-65.
5Swain, M. Communicative competence: Some roles of com- prehensible input and comprehensible output in its development. In Gass, S.and Madden, C. (Eds.), Input in Second Longuoge A eq uisition. New York:Newbury House, 1985.
