作者：刘文博
　　【Abstract】Stance bundles signal the mastery of a certain academic discourse and accordingly this study combined corpus data and interview data to compare the usages of stance bundles across different language proficiency. Through a corpus analysis， it was found that UG learners tend to give personal and overstated arguments， while TESOL learners demonstrate a better control of the examined stance bundles and use more phrasal varieties and fixed bundles. There was an incremental mastery of using stance bundles from the UG to TESOL level. It was suggested from the subsequent interview that factors such as instruction and L1 transfer might influence the use of stance bundles.
　　【Key words】Lexical bundles； Epistemic stance； Corpus analysis； English academic writing
　　【作者簡介】刘文博（1991.08-），女，汉族，天津人，南开大学经济与社会发展研究院，行政，硕士研究生，研究方向：语料库语言学与英语教学 。
　　1. Introduction
　　As a building block of English academic writing， lexical bundles signal the mastery of academic discourse and make writers as insiders of that community. Among the three functions that lexical bundles convey， epistemic stance function is a crucial area in academic writing， in which writers are required to balance facts and possibilities. It seems that， however， the use of stance bundles in L2 writing differs from L1 English writing and there appears to be inconsistent among learner groups with different proficiency levels. Therefore， the focus of this study is bundles with stance functions in L2 English writing.
　　Considering the fundamental role of both lexical bundles （e.g. O’Keeffe et al. 2007） and epistemic stance （e.g. Adel 2014） in academic writing， as well as the paucity of studies on L1 Mandarin-learner writing， this study investigated stance bundles in academic writing and endeavoured to make a contribution to raising L2 learners’ awareness of producing native-like stance bundles. Through corpus analysis， this study compared different usages of stance bundles between L1 English writers and L1 Mandarin-learners of L2 English at different proficiency levels （intermediate and advanced） and finally to explore some possible reasons for the differences.
　　2. Literature Review
　　In academic discourse， formulaic language has been seen as a cornerstone and tends to reduce language processing effort and thus increases language fluency and enables language production （Wary 2002）. Unlike the consensus on the importance， however， terminology of formulaic language tends to be varied， such as lexical bundles （Biber et al. 1999）， clusters （Hyland 2008） and formulaic sequences （Wray 2002）. The present study prefers to narrow down formulaic language as lexical bundles， referring to the recurring sequences that contain more than three words （Biber et al. 1999， p. 990）. Three discourse functions of lexical bundles （stance expressions，， discourse organizer and referential expressions） have been proposed by Biber and Barbieri （2007） with specific sub-types under each category， among which there is a growing focus on stance function in studies of academic writing， because L2 English learners seem to have difficulties in detaching writing persona and being objective （Adel 2014）， consequently resulting in informal writing styles.