This study investigated whether the effects of different types of corrective feedback (CF) (simple clarification request, enhanced prompt and elliptical elicitation) would differ on the acquisition of different types of grammatical structures. The target grammatical structures were verb endings (morphological morphemes) in three different English tenses including the simple present third person singular "-s", the present continuous verb formation marker "-ing", and the simple past verb ending" -ed". These targets were chosen because they are rather problematic for EFL learners to acquire. For this purpose, 31 L1 Persian EFL learners at intermediate level were given an opportunity to carry out some tasks and were provided with different types of CF on their erroneous utterances. Data analysis on the output accuracy following feedback on the three grammatical targets showed that the proportion of errors corrected in response to CF in the form of enhanced prompt was more than the proportion of errors corrected in response to the other two types of CF. These results suggest that the more explicit the CF, the more effective it would be in correcting language learners' erroneous utterances regardless of the type of given grammatical structure.