Trees are one of the oldest plants of our Earth. They keep our air clean, cut down noise pollution, improve water quality and give 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(刺) to tell 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 quickly and become strong enough to face challenges. At the age of 15, trees become young adults. They grow more slowly and bear 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 take good care of the adult tree, it will go on to live 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(空心的) or part of it becomes dead, it gives a home to small animals and food to 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 ▲ . So, let's enjoy every minute and face the challenges in life bravely!
①Grow very quickly ②Become a real adult ③Grow thorns
④Grow older and die ⑤Bear flowers and fruit
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