Models can/could, may/might, must/have to, ought to, would. 1. (stop) worrying so much. (it's my advice). 2. (eat) in the classroom. (it's not allowed) 3. our teacher says (finish) the report by friday. (it's necessary). 4. (rain) later, so bring an umbrella. (it's possible). 5. (walk) for hours when he was younger. (he was able to do it). 6. if you sit in front of a laptop for too long, (get) backache. (perhaps). 7. (respect) the others (it's our duty). 8. ) some coffee? yes, please.