1.
(2019·瓯海模拟)
—Could you please tell me _________________?
—They can be reused many times. In this way, we can help make the earth greener.
A . how often they walk to school
B . why we'd better use china cups and cloth bags
C . if you turn off the lights when you do not need them
D . why we divide the waste into plastic, glass, paper and rubber
