Answers to the questions:

1. Human beings, animals, birds, fish, insects and plants exist on the Earth.
2. Some species of animals and birds don't exist anymore because people have polluted their natural homes.
3. We see air and land pollution around us at present.
4. We shouldn't cut down trees because it's an international disaster. Even if new trees are planted, it takes many years for them to grow.
5. People pollute themselves with cigarettes, alcohol, and junk food. They breathe in the air polluted by their cars and factories.
6. I learned that pollution is very dangerous for wildlife and the environment.