1.Environmental protection is one of the most difficult problems to solve.
2.The rubbished littered everywhere will pollute the environment,do harm to people's health.So we'd better not litter anywhere as we like.
3.The rivers are dirty,fishes are dying and meanwhile trees are cut down.
4.We have only one globe,and we should protect it.We must try our best to make our home much more beautiful by keeping the environment clean and tidy.