This document provides a lesson on learning relative clauses in Chinese. It begins by giving examples of prepositional phrases used as adjectives to describe nouns. It then explains the difference between using prepositional phrases and relative clauses, with relative clauses allowing for more clear descriptions. The document outlines rules for determining which relative pronoun to use based on whether the antecedent is the subject, object, or possessor of a sentence. It provides numerous examples comparing prepositional phrases and relative clauses, and guides the reader on analyzing sentences to select the correct relative pronoun.