Complete the dialogue with the correct forms of 'have to'.

Zadie: Sorry, I can't see you on Saturday, Bella. Bella: Oh! Why? Zadie: I **have to help** (help) with the housework. Bella: (your brother / help) too? Zadie: No, he **doesn't have to**. He's too young. Bella: So, what **do you have to do**? Zadie: Vacuum the carpets, water the plants, feed the dogs. And I have to cook dinner. Bella: Why **do you have to cook**? Zadie: Because mum has to work. Bella: What about your mum? (she / work?) Zadie: Because she's a nurse, remember? She **has to** be at the hospital on Saturdays. Bella: (nurses / work) every weekend? Zadie: No, they **don't have to**. Only some weekends.