The document discusses the simple past tense in English. The simple past is used to talk about completed actions or events in a definite past time period. Regular verbs are conjugated by adding "-ed" in the affirmative form. Examples are given of affirmative sentences using the simple past with time expressions like "yesterday", "last night", and "last weekend". The document also covers forming negative simple past sentences using "did" plus "not" plus the base verb form, and provides negative example sentences. Finally, it lists common time expressions used with the simple past tense.