Class rules

OBLIGATION:                                                             PROHIBITION:
                                          
-You must be silent.                                            -You musin't speak in classroom
                                                                          
-You must listen to the teacher.                          -You musin't chew gum in       
                                                                            classroom.
-You must wort in class.                                    
                                                                           -You musin't play computer games
-You must play attention.                                    in classroom.

                                                                           -You musin't shout in classroom.