We live on a great planet called Earth. We must save it, because for example, oxygen keeps ecological balance in the nature. Look at the streets of your city. How many cars can you see? Nowadays, it is impossible to live without any transport. But cars, buses and the others send a lot of smoke into the air, which we breathe with. People destroy our green forests, they cut down millions of trees. As a result, many types of animals and birds lose their homes, and they disappear. We must save our environment!!!