摘要:AbstractIn this study researchers sought to find a relationship between second language instruction and learners’ productive use of 3rd person singular -s. Researchers collected written data from 151 participants in two phases in three different proficiency groups. Analysis of data showed that elementary learners are less developed in their interlanguage and are in lower levels of development based on Processability theory (1998, 2003). Advanced and intermediate learners are in fact in higher levels of processing capacity and can provide grammatical structures systematically.