Ответ:

  1. Graeme went online this morning and bought tickets for the concert.
  2. Simone and Kay were very busy all day yesterday. They didn’t have time for a break.
  3. Was Carly at the Science club last week? Did she give her presentation?
  4. Did you download those games recently? Were they free?

В Past Simple глагол be принимает формы was/were, а с остальными глаголами в вопросах и отрицаниях используется did/didn’t и начальная форма глагола.