This document discusses relative pronouns in Thai. It explains the different types of relative pronouns (who, that, which, etc.) and how they are used based on whether they are the subject, object of a verb, object of a preposition, or possessive. It provides examples for each case and notes that relative clauses should be placed next to the word they are modifying. It also discusses some rules for relative pronoun usage, such as always using "that" after superlative adjectives or ordinal numbers. Sample questions are provided to test understanding.