Shanghai cleaning service

The story of cleaning -- "Popular Science (Middle School Edition)", Issue 04, 1997

By Zhang Jin When looking at the Earth from a spaceship, it resembles a deep blue and translucent sapphire, shining with the light of human civilization and hope. In recent years, this "azure" planet has turned dark gray. The main reason for this result is that not only has the atmosphere been polluted, but also rivers, lakes, and oceans have been polluted.