просим всем классом чтобы нашелся умный человек,котрый решит это .если такой найдется то мы поставим свечки за ваше счастье
1. You mustn't / don't have to use the mobile phone on the plane. It's dangerous.
2. You look tired. You should / shouldn't go to bed.
3. Sasha could /couldn't swim a year ago, but now he can.
4. We don't have to / have to wear a uniform, so I normally wear sports clothes. 
5. You mustn’t / needn’t take an umbrella today. The sun is shining.