The past continuous tense, also known as the past progressive tense, is a verb tense used to describe an ongoing action that took place in the past. It is formed by combining the past tense of the verb "to be" (was/were) with the present participle (the base form of the verb + "-ing"). The structure of the past continuous tense is as follows: Affirmative: Subject + was/were + verb-ing Examples: I was studying when the phone rang. They were playing basketball in the park. Negative: Subject + was not/were not + verb-ing (or wasn't/weren't for contractions) Examples: She wasn't watching TV at that time. We were not expecting any visitors. Interrogative: Was/Were + subject + verb-ing + ? Examples: Were you sleeping when I called? Was he working late last night? The past continuous tense is often used to set the scene or provide background information in a narrative, to describe interrupted actions, or to talk about two actions that were happening simultaneously in the past. It emphasizes the duration of an action and is often used in conjunction with the simple past tense to provide a more detailed picture of events.