This document provides information about interrogative sentences. It begins by defining an interrogative sentence as one that asks a question and ends with a question mark. It then describes the different types of interrogative sentences, including 'Wh' type questions using words like what, when, who, why; 'Yes' or 'No' type questions using helping verbs; and tag questions. Characteristics of interrogative sentences are outlined, such as containing question words or auxiliary verbs. Examples are provided to illustrate each point. The document concludes by listing the 'Wh' words and common helping verbs used to form interrogative sentences.