The document discusses relative clauses and relative pronouns in English. It explains that relative clauses serve the same purpose as adjectives by providing information about a noun or pronoun in the main clause, called the antecedent. It then defines the relative pronouns who, which, that, when, where, whom, and whose and explains when to use each based on whether the antecedent refers to a person, animal, thing, time, place, or possession.

1. RELATIVE CLAUSES 4º eso