为了提高英语口语表达能力，假定你们班明天下午将召开依次以“Keep Our School Clean”为主题的班会，请根据以下要点用英语写一篇简短的发言稿。
1.在公共场所，不要随地吐痰，不乱扔垃圾。
2.不在墙上乱涂乱画。
3.坚持每天认真打扫室内外。
注意：1.词数在80词左右。
2.请不要逐句翻译。
3.发言稿的开头和结尾已为你写好。
Good afternoon,everyone.
We should keep our school clean.It's our duty .We shouldn't throw litter about and spit in public place.We shouldn't draw on the walls.We should sweep the floor every day.We should water floors every day.We mustn't walk on the lawn.We mustn't climb trees.We should do our best to keep our school clean.That is all.Thank you.