WHY DO LEAVES CHANGE COLOR IN THE FALL?秋天为何叶子变色？
Plants make their own food. They take water from the ground through their roots. They take a gas called carbon dioxide（二氧化碳） from the air. They turn water and carbon dioxide into food using sunlight and something called chlorophyll（叶绿素）. Chlorophyll is green. It gives leaves their green color.Winter days are short and dry. Many plants stop making food in the fall. The chlorophyll goes away. Then we can see orange and yellow colors. These colors were in the leaves all summer, but the green covered them up.
Some leaves turn red. This color is made in the fall, from food trapped（截留） in the leaves. Brown colors are also made in the fall. They come from wastes left in the leaves. When autumn comes winter will not be far away 学习了!谢谢! The world is changing and everything is changing. That's the circle of life, from birth to death. The important thing is the process of life. Spring, summer autumn and winter, the four seasons rotate every year. Spring is warm with everything coming back to life and tree leaves turn green. Summer is hot and tree leaves give shade to protect us from the strong sunlight. Autumn is cool and tree leaves change from green to red, yellow or other colors. In late autumn most tree leaves become dry and fall to the ground. That is why autumn is also called fall in American English. Winter is cold with strong wind sometimes. Tree leaves are gone. When it snows the world becomes white with everything covered with snow. That is the circle of seasons and life goes on and on like this, too. NOBODY will come to eat GREEN leaves, so, they turn brown.
页:
[1]