摘要：Several studies of the interlanguage of L2 learners of English have evidenced an interim stage in the development of preposition pied-piping and preposition stranding when learners tend to omit the preposition in both interrogatives and relative clauses. The phenomenon generally referred to as null-prep has been controversially discussed in the literature. Dekydspotter, Sprouse and Anderson (1998) have attempted to account for the phenomenon by positing the rule of preposition incorporation, hence accounting for their observation of asymmetrical behavior of arguments vs. adjuncts. However, Klein and Casco (1999) have presented evidence casting doubt on the speculated contrast between arguments and adjuncts and conjecture that null-prep is a consequence of null-operator movement operating similarly in both complement types. The present study examined the development of preposition pied-piping and preposition stranding in the interlanguage grammar of 80 Iranian participants at three proficiency levels and specifically focused on null-prep constructions in the participants' grammar to test the two conflicting hypotheses. The results showed that even though the Iranian EFL learners initially appeared to possess the subcategorization knowledge for the targeted verbs, they exhibited systematic and robust evidence of null-prep in both interrogatives and relative clauses across the two complement types, thus lending empirical support to Klein and Casco's analysis.
