Relative clauses join common information together in one sentence using relative pronouns like who, which, that, whose, where, and when. Defining and non-defining relative clauses are discussed along with quantifiers, gerund versus infinitive, modal verbs like should, must, can, could, may, and might, and linking words like whereas, while, although, even though, despite, and in spite of. The document provides an overview and review of these various grammar topics in preparation for an upcoming midterm test.