1.we should______water as it is a valuable resource.
2.we can help_____air pollution by driving less.
3.the paper we use comes from trees in ______.
4.we should_______our environment for a brighter future.
5.gas is a source of________.
6.mai po is a_________.
7.do not throw away plastic bags.we can______them.
8.we can help save many trees by___________(ryceclgin)paper