We are studying in this school. It is our duty to keep it clean and tidy. It is not good to spit in public places， such as in the library， in the class. We shouldn't leave rubbish here and there. Don't draw pictures on the wall， they influence the look of our school . We should keep the classroom clean and tidy. And we should do some cleaning often. If everyone tries his best to do something useful for our school， I'm sure our school will be more beautiful.