Long ago， Mother Nature gave each tree a different purpose． However， she did not share her sons with the trees．

   Fir Tree（杉树） had many tree friends．In summer，they watched Bird and Squirrel（松鼠）play in the field．Then autumn arrived．The leaves on other trees turned colourful．Fir Tree's leaves stayed green．Fir Tree told Mother Nature that he wanted his leaves to change colours too．

   "Be patient，" Mother Nature said． "You will learn your purpose．"

   So Fir Tree waited．The temperature dropped． Bird flew south， and Squirrel was nowhere around．All the trees lost their leaves except Fir Tree． Soon it snowed．Fir Tree cried，"Why don't I change like my friends？"

   "Be patient，" Mother Nature replied． " Soon you will get to know your purpose．"

   Just then， Squirrel appeared．She was cold．She asked if she could build a warm home in branches（树枝）．Other trees said no because they had no leaves． But Fir Tree said yes． Squirrel ran up Fir Trees branches． Soon， she was warm， comfortable and asleep．

   Fir Tree was happy that his green leaves provided a warm home for animals in winter． He finally understood his purpose．

（1）What did Fir Tree want to do in autumn？ （不超过10个词）

　　

（2）Why did other trees say no to Squirrel？ （不超过10个词）

　　

（3）What purpose did Fir Tree understand at last？ （不超过15个词）