任务型阅读。
June 5th is World Environment Day. This makes us pay more attention to our environment. When Wang Boxuan, a Beijing high school boy, uses up his exercise books, he does not throw them away. Each one is kept at his school with hundreds of exercise books that are given by other students. Then they are sold to a Beijing paper making factory.
The paper is recycled and used again by students and teachers in the school. At the same time, the money that is made from the sales goes to Inner Mongolia. The government there uses the money to plant more trees and grass. This place is one of the sources(源头)of the sandstorms that often attack Beijing during springtime.
Wang's school is one of the schools in the capital that takes part in the "green promise" environmental protection activity. So far, nearly 210，000 students have taken part in the activity, collecting more than 87 tons of waste paper.