March 22 is World Water Day. It started in 1993. It not only makes us think about the importance of water, but   also calls on（号召）us to___and protect water. Today, we're facing terrible water problems. Among them, the wastewater problem is rather ___, And the subject of World Water Day in 2017 is “wastewater”.

What is wastewater? It is used water.   Usually, wastewater comes from homes,___, hospital and so on. It is produced by different kinds of activities, including washing machines, taking showers and using kitchens. The rain also___wastewater when it is running down the street during a storm. No matter where it comes from, this kind of water is sure to have____harmful in it．

___must we treat（处理）wastewater? Wastewater has a big influence in our lives. It causes both illness for us and pollution for the environment. We must care for our environment and our own___.

How can we treat wastewater? Different kinds of wastewater need different ways of treatment. Wastewater___homes can be reused. Then there will be___wastewater. Also, factory wastewater has to be cleaned____it goes back to nature.

June 5 is World Environment Day. Wang Boxuan is a high school student in Beijing. When he uses up his exercise books, he doesn’t throw them     26    . Each one is     27     (store) at his school. There     28     (be) hundreds of exercise books given by other students. Then they are sold     29     a Beijing paper making factory. The paper is recycled and     30     (reuse) by the students. At the same time, the money made from the sales     31     (go) towards schools in Inner Mongolia for     32     (plant) trees and grass. Wang Boxuan’s school is one of the schools that take part     33     the “green promise” environmental protection activity. So far,     34     (near) 210,000 students have been members of the activity. They collect more than 87     35     (ton) of waste paper.