----- Nội dung dịch tự động từ ảnh ----- 6. I book the tickets in advance. (don't have to) Alia, you say rude words like that. (mustn't) 8. We play table tennis. We can play chess instead. (don't have to) 9. Children put their hands into sockets. That is very dangerous. (mustn't) 10. Doctors sometimes work at the weekends and on national holidays. (have to) 7.