Trees have a very close relationship with people, and they play an important role in nature: they can photosynthesize, absorbing waste gases from the air and converting them into fresh air for the living creatures on earth. In addition, the roots of trees can penetrate deep into the ground and hold the soil firmly, preventing the soil from being washed away by rain, avoiding the occurrence of road slumps and landslides, and contributing to soil and water conservation. Moreover, trees have a wide range of uses, as they can be made into furniture, pencils and paper. Large trees can provide shade, and fallen leaves can be used to make paper.