Past Simple: negatives and questions (did / didn't)

Rules

• Rule 1: Negative → didn't + base verb

  In a negative sentence didn't comes after the subject, then the verb in its base form. didn't already shows the past, so no -ed and no irregular form.

  Pattern: subject + didn't + base verb

  Example: She didn't eat her soup.

  Example: We didn't play outside.

• Rule 2: Question → Did + subject + base verb

  A question starts with Did, then the subject, then the base verb again. We use Did for every subject.

  Pattern: Did + subject + base verb …?

  Example: Did you finish your book?

  Example: Did the cat catch the mouse?

• Rule 3: Short answers

  For a short answer to a Did question we don't repeat the verb; we just say did or didn't.

  Pattern: Yes, subject + did. · No, subject + didn't.

  Example: Did you like the book? — Yes, I did.

  Example: Did they win? — No, they didn't.

• Rule 4: With question words

  Question words like What, Where, When, Why, How come before did.

  Pattern: question word + did + subject + base verb …?

  Example: Where did you put my pencil?

  Example: What did she say?

• Rule 5: was / were don't need did

  When the sentence has no main verb (just an adjective or a place) we use be: I wasn't tired. Were you at home? We don't use did here: ~~I didn't tired~~.

  Pattern: was / were + (not) + adjective / place

  Example: I wasn't tired after the walk.

  Example: Were you at the library?

Common mistakes

• I didn't went to school. → I didn't go to school.

  didn't already shows the past; the verb stays in the base form.

• Did you saw the movie? → Did you see the movie?

  After Did use the base verb: see.

• She not liked it. → She didn't like it.

  not alone isn't enough in English; we need didn't.