This document provides definitions and explanations of key concepts related to sentences in the English language. It discusses the components of a sentence, including the subject, verb, object, complement and other parts. It also classifies sentences based on meaning into statements, questions, commands, exclamations and optatives. Additionally, it examines sentence structure types such as simple, complex and compound sentences. The document aims to outline the basic structures of simple declarative sentences for communicative English. It concludes by explaining the eight parts of speech that words in a sentence can belong to.