Kindly warnings:
教室:Success comes from hard work/Study hard/Value the time/Nothing is too difficult if you put your hard in it/There is nothign hard for a willing heart.
洗手间:Save the water/Water is the source of life/Close it after using it/
走廊:Be quiet/Don't make any noise
楼梯:Mind your steps/Be quiet/Don't make any noise