as we all know, trees are very useful. they are of great benefit to man as follows: first, trees provide us with wood and other products; second, their roots can allow the rain to sink in and keep the soil, so they help to prevent droughts and floods. trees can clean air and beautiful life.

　　unfortunately, nowadays in many parts of the world lots of people fail to realize the importance of trees. they have cut trees down in large numbers without a plan,which makes the soil washed away. they don't know where there no trees, the rain washed away the surface of the soil and this causes floods.

　　we ought to plant trees each year and carefully look after new trees in order not to make the forest slowly disappear. only' in this way can we make the forest serve man forever.