We ...come to classes on time.
must
We ... fail the test.
mustn't
We ... be noisy.
mustn't
We ... take part in project work.
must
We ... put the hand up to speak.
must
We ... listen to the teacher.
must
We ... interrupt other students.
mustn't
We ... behave well.
must
We ... mustn't bully other students.
mustn't
We ... come late for classes.
mustn't
We ... work together with the class.
must