Надо! what must they do in these situations? write questions and answers using must or mastn't. 3. sam is i'll. 4. my brother is going to leave very early tomorrow. 5. a man sees a house on fire. 6. you see a crying child lost in the street. use the following phrases call a doctor ) buy a present call the firemen) help him find his stay up late )way home ) go to bed early