3. 1)change, remain
2)clean up, pollute
3)prevent, let
4)improve, get worse
5)plant, cut down
6)recycle, throw (them) away
7)save, waste
8)destroy
4. 1)were discussing
2)were talked about
3)is growing
4)Have (you ever) heard
5)is being planned
6)has already been published
7)were included
8)is being prepared
6. 1)is 2)combines 3)collect 4)bring 5)save up? 6)spend 7)opens 8)gather 9)waiting 10)fills 11)? 12)trade? 13)have 14) carries?