Trees live on the earth much earlier than humans.They help to keep the air clean，reduce noise pollution，stop sand from （1）

moving

moving

（move），improve water quality，give us food and provide building materials.
   Trees change a lot when they grow like a person.Young trees learn to protect （2）

themselves

themselves

（they） during the first three years.For example，some trees grow thorns （刺） so that （3）

none

none

/n?n/of animals can hurt their skins.Most trees have large， （4）

deep

deep

/di：p/green leaves to catch sunlight and change it into their food and energy.
   Trees grow （5）

rapidly

rapidly

（rapid） and become strong enough at the age of four.Trees become young （6）

men

men

（man） when they are fifteen years old.At this period，they grow more slowly and （7）

produce

produce

/pr?'dju：s/ flowers and fruits.
   A tree can grow up like a real man when it is twenty to twenty-five years old.The tree has its largest size.It gives us a place to rest，read a book，listen to music （8）

or

or

drink tea.From now on，a tree begins to grow older and older and even die.But a tree is still important in nature.It provides food （9）

for

for

many animals.
   In many ways，the life of the tree is （10）

the

the

same as us.From the life of a tree，we have learnt that each period of life brings us different joy and experience.