in the context of the epp, the existence of subject and object control follows naturally from the fact that the null pronominal subject pro can be co-indexed with different dp arguments. while (1a) and (2a) show the surface sentences, (1b) and (2b) show the more abstract structure where pro serves as the subject of the non-finite clauses, thereby satisfying the epp-feature of t (realized by infinitival 'to'). the following tree diagrams of examples (1) and (2) show how pro occupies the subject position of non-finite clauses.