III.    Choose the correct answers. of trees. 
11.    If we        waste paper, we will save a lot of trees.
    A.repeat    B.recycle    C.rewrite    D.remake
12.    If we plant more trees inthe schoolyard, the school will become a         place.
    A.greener    B. darker    C. dirtier    D.more polluted
13.    "Why do you often forget to        the lights when you go out of the classroom?"
    A.turn on    B.turn off    C.close    D.shut down
14.    "What can we do        air pollution?"
    A.reduce    B.to reduce    C.reducing    D.to reducing
15.    You can save money while shopping by only buying        you need.
    A. what    B. it    C. this    D. that
16.    "Reduce, reuse, recycle" is said to encourage people to waste less, by using less and using things again, in order to         the environment .
    A. harm    B.damage    C.pollute    D.protect
17.    Please collect all the recyclable materials, and take them to the        factory.
    A.recycle    B.recycled    C. recyclable    D.recycling
18.    This newspaper is made of        paper.
    A.recycle    B.recycled    C.old    D.waste
19.    If we all use        bags, we'll help the environment.
    A.new    B.cheap    C.reusable    D.reduced
20.    These three Rs         . reduce, reuse, and recycle
    A.stand up    B.stand for    C.ask for    D.means
21.    If there is a rubbish bin in every class, the classroom will become        .
    A. harmful    B. lighter    C. dirtier    D. cleaner
22.    "Don't throw rubbish into the river because you will make it        ."
    A. greener    B. dirty    C. cleaner    D. fresher 
23.    If we use        paper, we will save a lot of trees.
    A.fewer    B.less    C.more    D.much
24.    You should put the food in a reusable box        plastic bag.
    A. by    B.instead of    C.because of    D.without
25.    If people turn off all electric appliances in one hour all over the world, they can save lots of        .
    A.electric    B.electrical    C.electrician    D.electricity