根据对话内容，从下面方框中选择适当的单词或短语填空，使对话内容完整正确
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A: Hey! I met a student from a green school in Dalian.
B: A green school? 1 is it?
A: It is a school which supports the protection of the environment. In fact, there are 2 green schools in China. It’s wasteful to throw away glass, paper and metal, 3 every class in such schools collects waste that can be used again and then sells it for recycling（再利用）。
B: Great! What else do they do?
A: They also save energy and tricycle things at home, such as 4 lights and saving water.
B: If everyone tries to protect the environment, we will make the world much better.
A: I agree. If we don’t, the future is 5 .
B: Anyway, public concern over the environment has greatly increased. There is hope for the future.