The document discusses the past continuous tense. It explains that the past continuous describes an action that was in progress at a specific time in the past. It can be used to describe an interrupted action or two simultaneous past actions. The document provides examples of how to form past continuous sentences, including negatives, yes/no questions, wh-questions, and tag questions in the past continuous tense. It concludes with exercises for the reader to practice forming sentences in the past continuous.