Joke Collection Website - News headlines - How to write a slogan that forbids loud noise?

How to write a slogan that forbids loud noise?

If the water is not deep, the dragon is the spirit; If the sound is not high, it will be fine if there is sound < P > Speak louder in class; Be quiet after class.

your whispering is a respect for everyone.

in the future, let's cheer loudly; Today, let's study quietly.

is that enough?