This study aims to investigate the acquisition of English verb morphology by learners of two typologically different L1s and the role of L1 transfer in the acquisition pattern, a cross-sectional study (n = 180) carried with Chinese and Mongolian college students learning English at two proficiency levels, using the cloze passage and composition. 120 cloze passages and 20 compositions were selected as data to be analyzed. Consistent with the Aspect Hypothesis, the results of MANOVA tests show a significant effect of lexical aspect on tense-aspect marking use: the perfective and past markings are strongly associated with Achievements/Accomplishments; the progressive marking is strongly associated with Activities; the present marking is strongly associated with States. Even though Mongolian and Chinese learners show virtually the same acquisition pattern, their performances in using the past, perfective, and progressive markings are different. Mongolian learners exhibiting superiority over Chinese learners in associating and correctly using the perfective and progressive markings, overuse of progressive markings by Mongolian learners, and overextending progressive markings to States by both L1 groups evidence L1 transfer. Contradictory findings-greater use and correct use of past markings with States than with Activities, overextending progressive markings to States, and learners' preference for using progressive markings with Achievements to Accomplishments suggest that the methodology, L1, sentence structures and input may somewhat affect the results of tense-aspect marking studies.

This study aims to investigate the acquisition of English verb morphology by learners of two typologically different L1s and the role of L1 transfer in the acquisition pattern, a cross-sectional study (n = 180) carried with Chinese and Mongolian college students learning English at two proficiency levels, using the cloze passage and composition. 120 cloze passages and 20 compositions were selected as data to be analyzed. Consistent with the Aspect Hypothesis, the results of MANOVA tests show a significant effect of lexical aspect on tense-aspect marking use: the perfective and past markings are strongly associated with Achievements/Accomplishments; the progressive marking is strongly associated with Activities; the present marking is strongly associated with States. Even though Mongolian and Chinese learners show virtually the same acquisition pattern, their performances in using the past, perfective, and progressive markings are different. Mongolian learners exhibiting superiority over Chinese learners in associating and correctly using the perfective and progressive markings, overuse of progressive markings by Mongolian learners, and overextending progressive markings to States by both L1 groups show evidence of L1 transfer. Contradictory findings are greater use and correct use of past markings with States than with Activities, overextending progressive markings to States, and learners' preference for using progressive markings with Achievements to Accomplishments, which suggest that the methodology, L1, sentence structures and input may somewhat affect the results of tense-aspect marking studies.