In recent years, China's many cities are being tortured by smog. Development is always accompanied by pollution.This may be difficult to solve in the shore term,but we must address it for the future. It is time to fear what harm pollution will do to us and to the earth. It is time to cherish the blue sky and white clouds and returns to pollution free days; we hope that the blue sky and white clouds do not only can exist in the countryside, but also can return to our urban environments as soon as possible.