As a student ,it's our duty to keep our school clean, on one hand ,we should not spit in a publlic place ,on theother hand ,we can't draw on the wall. what's more ,we must not throw rubbish onto the ground , but it is not enough for us to do this ,we need to make a rule about keepingour school clean,if someone doesn't obey it,he or she will be punished.in my oppion,all of us do some cleaning ,do some useful ,I am sure that our school will be clean everyday.