This document discusses the use of relative pronouns - where, that, and which - in sentences with embedded clauses. It provides examples of when to use each pronoun based on whether the embedded clause includes a preposition or not. Specifically, it notes that "where" should be used when the embedded clause includes a preposition, while "that" or "which" should be used when there is no preposition in the embedded clause. The document also discusses keeping or replacing prepositions in some examples and provides practice identifying the main sentence, embedded clause, and selecting the correct relative pronoun to use.