Can and Could in Academic Writing: A Corpus-Driven Comparison of English L1 and Vietnamese EFL Students

The English modal system is complex, and linguistic descriptions of the modals present varied accounts of the meanings that modal verbs express. It is therefore unsurprising that English modal auxiliaries can present difficulties for language learners. Focusing on can and could, this article uses the highly graded academic writing in the Michigan corpus of upper-level student papers (MICUSP) to describe epistemic modal use of can and could by L1 writers. This description is then employed in analysing the use of can and could in academic writing by Vietnamese learners of English, and in discussing atypical uses. Our analysis found that atypical uses of could involved the use of could to express meanings in contexts where likelihood was relatively high, making can more appropriate. Based on this analysis, pedagogical applications are suggested for English language teaching.