giải giúp mình câu này với ạ

1. Bookings need to be made at least seven days before departure. 2. In most developed countries, people don't need to boil water before they drink it. 3. You needn't go on the beach when the tide's coming in. It's very dangerous. 4. I often have to work at the weekend to get everything done. 5. Changes in technology needn't be a problem, but could be seen as a great opportunity. 6. We've been told that we don't have to be at work until 10:00 tomorrow. 7. When you have time, we have to get together for a weekend. 8. We mustn't allow our speed of production to drop. 9. As you worked late yesterday you needn't come until 10:00 tomorrow morning. 10.Employees will have to accept the new conditions or be dismissed. 11.Of course the first thing I did was to call the police and I didn't have to wait very long for them to get there. 12.You don't need to have a university degree to become a police officer. 13.Nowadays it needn't cost a fortune to own a powerful computer. 14.I don't have to remind you that we are competing with two other companies.