2015职称英语考试用书理工类最全新增文章节.doc

关注微信订阅号号：hbwypx 2015职称英语考试用书理工类更新5篇 旧文章新增文章理工C阅读理解第九篇：Egypt Felled by Famine第九篇：An Essential Scientific Process补全短文第五篇：The Magic of Sound第五篇：A Record-Breaking Rover理工B阅读理解第二十二篇：Snowflakes第二十二篇：Real-World Robots补全短文第九篇： Heat Is Killer第九篇：Lightening Strikes理工A补全短文第十三篇：Sleeping Giant第十三篇：Affectionate Androids理工C级阅读理解新增文章（河北师大外院培训中心提供 HYPERLINK . qq469296725）第九篇? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ? An Essential Scientific ProcessAll life on the earth depends upon green plants. Using sunlight, the plants produce their own food. Then animals feed upon the plants. They take in the nutrients the plants have made and stored. But that’s not all. Sunlight also helps a plant produce oxygen. Some of the oxygen is used by the plant, but a plant usually produces more oxygen than it uses. The excess oxygen is necessary for animals and other organisms to live.The process of changing light into food and oxygen is called photosynthesis. Besides light energy from the sun, plants also use water and carbon dioxide. The water gets to the plant through its roots. The carbon dioxide enters the leaves through tiny openings called stomata. The carbon dioxide travels to chloroplasts, special cells in the bodies of green plants. This is where photosynthesis takes place. Chloroplasts contain the chlorophylls that give plants their green color. The chlorophylls are the molecules that trap light energy. The trapped light energy changes water and carbon dioxide to produce oxygen and a simple sugar called glucose.Carbon dioxide and oxygen move into and out of the stomata. Water vapor also moves out of the stomata. More than 90 percent of water a plant takes in through its roots escapes through the stomata. During the daytime, the stomata of most plants are open. This allows carbon dioxide to enter the leaves for photosynthesis. As night falls, carbon dioxide is not needed. The stomata of most plants close. Water loss stops.If photosynthesis ceased, there would