You should study if you want to pass the exam. (better)
You'd better hurry if you want to pass the exam.
Maybe they forgot about the appointment. (might)
They might have forgotten about the appointment.
Do you have permission to stay out late? (allowed)
Are you allowed to stay out late?
They shouldn't spend so much time on their phones. (supposed)
They aren't supposed to spend so much time on their phones.
