It is reported that ten big cities in China are being ranked among the top twenty cities with the highest pollution index in the world. This means it is high time we did something to bring the situation under control. Many factors are contributing to the deteriorating situation. For example, industrial wastes pumped into the air, the lakes and rivers; an increasing number of automobiles crowding into the streets; the widespread use of plastic bags, etc. Therefore, how to solve the problem of ...
