1. Smoking is not allowed in the hospital (must) => You 2. It isn't necessary for you to book the tickets (have to) => You 3. You are not allowed to park here (must) => You 4. It is better for parents to take time to understand their children (better) => Parents had

1. You mustn't smoke in the hospital. ( mustn't : không được phép)

2. You don't have to book the tickets. ( don't have to : không cần phải)

3. You mustn't park here. ( mustn't : không được phép)

4. Parents had better take time to understand their children. ( had better V = should V)