Do you have any unforgettable thing? Certainly I think, so do I. Last spring, on a sunshine day, our students and teachers visited East Park. When we went into the park, we saw many colorful flowers and several beautiful butterflies dancing on the flowers, even the little bees were attracted by such beautiful scene. Suddenly, we smelled the stinking air. We all frighted and looked for the reason. On the back of a food shop, there were many plastic bags and bottles with dirty oil floating on the lake. We all felt angry. We thought we must do something to change the situation.