6Brennan M & Van Naerssen M. Language and content in ESP [J]. ELT Journal, 1989, 43(3) : 196-205.
7Hutchinson T & Waters A. English for Specific Purposes. A Learning-centered Approach [ M ]. Cambridge : Cambridge University Press, 1987.
8Strevens P. ESP after twenty years : A reappraisal [ A ]. In Tickoo M ( ed. ). ESP: State of the Art [ C ]. Sin- gapore: SEAMEO Regional Centre, 1988. 1-13.
