1Pawley,A. & Syder,F. H. Two puzzles for linguistic theory: Native-like selection and native-like fluency [J], Language and Com-munication ,1983: 191-226.
2Biber, D.,S. Johansson, G. Leech,S. Conrad, & E. Finegan. Longman Grammar of Spoken and Written English [M], Harlow:Pearson, 1999.
3Biber, D. University Language: A Corpus-Based Study of Spoken and Written Registers[M]. Amsterdam: Benjamin, 2006.
4Hyland, K. As can be seen: Lexical bundles and disciplinary variation [J]. English for Specific Purposes, 2008, 27( 1 ):4-21.