Ahmad Alibabaee - Assistant Professor University of Isfahan
Manizhe Youhanaee - Assistant Professor University of Isfahan
Mansoor Tavakoli - Assistant Professor University of Isfahan

The present study sought to investigate the acquisition of referential, quasi and expletive subject pronouns, three different types of obligatory subjects in English, by adult Persian speaking L۲ learners of English at different stages of L۲ acquisition. A Grammaticality Judgment Test and a Translation Test were designed and developed to elicit the participants' knowledge of obligatory subjects in English. The results revealed that the L۲ learners conformed to the natives in their performance on obligatory referential subjects and obligatory expletive subjects, but they did not conform to the natives in the case of obligatory quasi subjects. The obtained results can be accounted for by the fact that Persian as the L۲ learners’ native language accepts referential and expletive subjects in certain structures, but no quasi subjects exist in Persian. This lends support to Smith and Tsimpli (۱۹۹۵) and Hawkins and Chan (۱۹۹۷) in that adult second language learners are not able to modify those functional features not already encoded in the entries of their native language.

expletive subjects, quasi subjects, referential subjects, second language acquisition