How to protect the environment becomes one of the biggest problems in the world. We can find that rubbish not only pollutes our environment but also harms our health. So we should not throw rubbish onto the ground. Some factories are pouring waste water into rivers， lakes and fields. It can pollute plants; sometimes it can kill lots of fish. We must keep our environment clean and tidy. We must try our best to protect the earth， and make our home more beautiful.