摘要：The current research examines the immediate and delayed effects of three types of corrective feedback, namely recasts, metalinguistic feedback, and clarification requests, on the acquisition of English wh-question forms by Iranian EFL learners. To this end, 134 Iranian EFL learners comprising 4 intact classes participated in the study. Learners in 3 intact classes which were designated as feedback groups received feedback during a meaning-focused task, while learners in the control group received no feedback. The results of data analysis revealed the effectiveness of metalinguistic feedback and recasts in both immediate and delayed post-tests. Further inspection of the results revealed that while metalinguistic feedback was more effective than recasts in the immediate post-test, recasts had a more stable and enduring effect, compared with metalinguistic feedback, on learners' performance in the delayed post-test.
