The document explains the past continuous tense, which is used to talk about actions that were ongoing or in progress at a specific time in the past. It provides examples of using the past continuous ("was/were + verb+ing") in sentences. It also notes that the past continuous can be used along with the past simple tense to talk about a shorter action that occurred during a longer ongoing action. The document includes exercises asking the reader to provide the missing verbs in sentences using the past continuous tense.