Hi !
Obligation : You must be respectful to everyone in the school at all times. You have to be polite. You must be on time for class. You always have to keep the class clean.
Prohibition : You must not chew gum in P.E. You must not eat during class. You must not cheat in tests. You must not make fun of/bully anyone.
Strong recommendation : You should ask for help if you are struggling on something. You shouldn't give up. You should read again your lessons before class.
