Trees are one of the oldest "citizens" of our earth． They keep our air clean，reduce noise pollution，improve water quality and provide food and building materials．

Just like us，trees change a lot as they grow．At 1 to 3 years old，young trees learn how to grow up safely．For example，many trees grow thorns to warn animals not to go near．Most young trees have large，deep green leaves so that they can catch enough sunlight and change it into their food and energy．

When trees are 4 years old， they begin to grow very rapidly and become strong enough to face challenges later in life． At the age of 15， trees become young adults． They grow more slowly and begin to produce flowers and fruit．

It is not until the tree is 20 to 25 years old that it becomes a real adult．The tree reaches its largest size．The adult tree gives us shade，oxygen and natural beauty．It is also a great place for a tree house，or a place for us to read a book， listen to music and so on． If we give the adult tree proper care， it will go on to live healthily for many years．

Gradually， trees begin to grow older and older and even die．At this time， they still have their important place in nature．When a tree becomes hollow or part of it becomes dead， it provides a home for small animals and is a source of food for many other animals．

In many ways， the life of a tree is similar to our own life experience． When we are looking at the life of a tree， we learn that each period of life brings its own form of joy and challenge． Enjoy every minute of the life of the trees and look after the trees!

                                                     The（1） 　　of a Tree

Something useful	Improve the environment and offer（2） 　　and materials for building．
Changes as they（3）	1 ﹣3 years old	Learn ways to grow up（4） 　　．	Grow thorns to warn animals．
			Catch enough sunlight with large green leaves．
	4 years old	Grow quickly and become（5） 　　．
	（6） 　　years old	Grow slowly and produce flowers and fruit．
	20﹣25 years old	Become real（7） 　　．	Give people a lot such as oxygen and good places to relax．
			Live longer if people take（8） 　　of them properly．
	Grow older or die	Be still（9） 　　in nature．
Conclusion	A tree's life is the（10） 　　as our life experience in many ways．