3Tarone E, et al. On the Use of the Passive in Two Astrophysics Journal Papers [A]. In Swales J. Episodes in FSP[M]. Hemel Hempstead: Prentice Hall International (UK) Ltd, 1988. 191 -202. 被引量：1
4Sinclair J. Collins Cobuild English Dictionary[Z]. London: HarperCollins Publishers Ltd, 1995. 被引量：1
5Aristotle. Rhetoric[M]. New York: The Modem Library,1954. 被引量：1
6Swales J. Genre Analysis[M]. Cambridge:CUP, 1990. 被引量：1
7Skelton J. Care and maintenance of hedges[J]. ELT Journal, 1988, 42(1):37-43. 被引量：1
8Salager-Meyer F. Hedges and Textual Communicative Function in Medical English Written Discourse[J]. English for Specific Purpose. 1994, 13(3): 149 - 170. 被引量：1
9Crismore A, Fransworth R. Metadiscourse in Popular and Professional Science Discourse[A]. In Nash. W. The Writing Scholar: Studies in Academic Discourse[M]. Newbury Park, CA: Sage. 1990,130- 140. 被引量：1
