Don't spit on the floor.
Don't litter.
Don't make too many noise.
Don't fight.
Don't shout at others.
We should obey the rules.
We'd better wear school unfrom.
We'd better be on time to school.
We should get on well with others.
It's important for us to study hard.
It's important for us to finish our homework by ourselves.
We should respect the teachers.
We should build our bodies.