| Studies found EL learners overuse and as an additive connector at the sentence-initial position (Bolton, Hung, & Nelson, 2002), and they underuse and as a coordinator (Leung, 2005). Generally, the use of the and-coordinator has often been overlooked in corpus research and in English teaching because of its seemingly simplicity. To test previous findings about the and-coordinator and to examine the influence of English proficiency on the use of and in academic writing, three learner corpora—MICUSP-NNS (advanced level), MICUSP-NS (advanced level), and NUCLE-NNS (upper-intermediate) were compared, with regard to the use of (a)symmetric structures of the and-coordination. Each corpus contains 31 argumentative essays written by 31 university students.;One-way ANOVA and Kruskal-Wallis tests indicated more evidence is needed to determine whether learners at advanced and upper-intermediate levels use total and-coordinators differently. More evidence is also needed to decide if the three groups use the and-syntactically symmetric coordination differently. Students at the upper-intermediate level, however, use and-asymmetric structures significantly less than those at the advanced level. A subsequent qualitative analysis reveals their use of and shows more repetition and redundancy. Possible reasons for why they employ asymmetric and-coordination much less frequently includes the lack of knowledge of certain grammatical structures, the insufficient knowledge of the writing topic, the impact of instructions, and language transfer.;An implication of the study is and-coordination should be taught at all levels of proficiency and should be integrated into the teaching of other grammatical structures. When students' use of and shows unskillful repetition and redundancy, teachers might need to help students acquire knowledge of other structures and the academic topic they are writing about. Future studies can examine how differently learners at various proficiency levels use and in connecting different types of phrases and clause and what the relationship between parallelism and syntactic asymmetry in the and-coordination is. |
