树的一生

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 protect themselves. 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 to 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 about that each period of life brings its own form of joy and challenge.

Enjoy every minute of the life of the trees and take care of the trees！

樹是地球上最古老的“居民”之一。它们能净化空气，减少噪音污染，提高水质，以及提供食物和建筑材料。

就像我们人类一样，树在生长过程中也会发生很多变化。1—3岁时，小树们会学习如何保护自己。比如，许多树会长出刺，以此来警告动物不要靠近它们。大多数小树长着大大的深绿色的叶子，这样它们就可以吸收足够的阳光并转化为自己所需的食物和能量。

当小树长到4岁时，它们会进入快速生长阶段，树干变得更加坚固，足以抵御未来可能面临的危险。到15岁时，树就“成年”了。这时它们的生长放缓，开始开花结果。

不过，到20—25岁时，树才算真正地长大，长成一棵棵参天大树，为我们提供荫凉、氧气和宜人的自然风光。这时候的树可以做成树屋，也是我们进行阅读、听音乐等的好去处。如果我们给予妥善照料，它们会健康生长很多年。

慢慢地，树开始逐渐变老，有的甚至会“死”去。这时候，它们在自然界中仍然发挥着重要作用。当树内部空心或部分已经枯萎时，它们便成了小动物的栖息地，也是许多其他动物的食物来源。

在许多方面，树的一生都和我们人类相似。当我们观察树的一生时，我们了解到人生的每个阶段都会带来不同的欢乐和挑战。

让我们珍视树的生命，保护树木！

Vocabulary

reduce v. 减少，缩小

thorn n. 刺，棘刺

hollow adj. 中空的;空心的

source n. 来源;出处