This document discusses the different types of past tenses in English: past simple, past continuous, past perfect, and past perfect continuous. It provides the formulas, examples, and uses for each tense. The past simple is used for completed past actions or past habits. The past continuous describes an ongoing action in the past. The past perfect expresses an action that occurred before another past action. And the past perfect continuous is used for an action that began in the past and continued up until another time.