(keep distance)
You must keep distance.
(feed)
She must feed her dog.
(use your phone)
You mustn't use your phone in the car.
(uniforms)
They/We/You must wear uniforms.
(cheat in exams)
You mustn't cheat in exams.
(eat)
You must eat fruit and vegetables/healthy food.
(listen)
You mustn't listen to music in class.
(uniforms)
They/You don't have to wear uniforms.
(homework)
She must do her homework.
(listen)
You must listen to this CD.
(smoke)
You mustn't smoke.
(study)
She doesn't have to study. / You don't have to study.
(turn on)
You must turn on your camera.
(at the weekend)
You don't have to wake/get up early at the weekend.
(speak)
You mustn't speak.