Скажите,что ученики должны сделать?Ученики должны хорошо учиться.

Say what students need to do? Students should study well.

Pupils must not take pets to the lesson, speak loudly, sleep in the classroom, draw on the desks и т.д.

Pupils must listen to the teacher, be polite to other classmates, answer the teacher*s questions и т.д.