We can see trees here and there. Trees are important in the world. They are useful to man in three important ways. First, they give man food, wood and clean air. Trees give man food and they give many animals food, too. If there are no trees, many animals can't live. And it's not easy for man to live. Second, trees can give us _ . On a hot summer day, children would like to relax under the shade of a tree after they play for a long time. Third, trees can help to stop bad weather. But in many places , people cut down a lot of trees. And then the weather gets bad. Trees can make the weather  _  .
cold warm good bad