Trees are our best friends. They are one of the oldest livings on the Earth. They absorb harmful gases from the air and release oxygen back into the air. They can cool the air as well. They can also make our streets more beautiful and less noisy. They provide food and shelters for some animals. We can use wood to make a lot of things, such as furniture, paper and so on. Without trees, the Earth would be too hot to live on. The soil would be washed away. We can hardly find food to eat. We would in great danger. Because of these, we should protect trees from cutting down them. We should plant more trees. They are the best fighters against pollution. They are our friends.