Fill in: "have to" (or its negative form) in the Present Simple or Past Simple.Fill in: "have to" (or its negative form)

1) We don\'t have (Present Indefinite) to come to school on Saturdays and Sundays. 2) A teacher has to (Present Indefinite) correct a lot of exercise-books. 3) We missed the bus, so we had to (Past Indefinite) take a taxi. 4) She didn\'t have to (Past Indefinite) do any homework because she wasn\'t at school.