Table of Contents - 8[-]Introduction - 14[-]Ch.1: Gaps and Parasitic Gaps - 20[-]Ch.2: HET as a Referential Expression - 106[-]Ch.3: The Adverbial Pronoun ER - 184[-]Ch.4: Some Related Topics - 272[-]References - 342In this study the syntactic properties of empty categories and dummy pronouns are investigated within the framework of Government-Binding theory. The assumption that clauses must have a subject is present in most, if not all, linguistic theories. In GB theory the requirement that clauses have a subject is stipulated as a consequence of the base rul