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