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ACID RAIN: What's the Solution? One of the wildest regions in the U.S., far from civilization, is the Adirondack area of northern New York State. For years this isolated spot has had the reputation of being one of best fishing spots in the U.S. As a boy 30 years ago, Bill Marleau first through the Adirondack wilderness near his small cabin on Woods Lake. Thousands of sportsmen have stayed at his father's lodge nearby. But now Bill's 134 hectares (335 acres) of lakefront land have only scenic value. Gone are those huge trout that used to swim in the turbulent, nutrientrich water a short distance from his doorstep. Gone from the cool nights are the sounds of thousands of frogs and toads. And gone are the birds that once fed on those water creatures. Occasionally Bill sees a lone fisherman fruitlessly cast his bait into the empty waters of old lake. 'I just don't have the heart to tell,' he said. 'This old lake's dead. It was killed years ago by acid rain.' What is acid rain? Acid rain is a popular term for precipitation in the form. of rain, sleet, snow or hail that is more acidic than normal. Acid rain is produced when atmospheric moisture combines with pollutants from power plants, factories and automobiles. When fossil fuels such as coal and oil are burned, sulfur dioxide and nitrogen dioxide are produced. These two gases react with the water and oxygen in the atmosphere to form. droplets of weak sulfur and nitric acid. Carried by prevailing winds and weather conditions, clouds containing these droplets travel hundreds, sometimes thousands, of kilometers from the source of the pollutants. Recently scientists found that acid rain now affects huge areas of the North Hemisphere. Power plants and factories in the heavily industrialized regions of Ohio and Indiana are believed to be the source of the acid rain that killed Woods Lake along with hundreds of others in New York State and eastern Canada. Acid haze over Alaska is believed to come all the way from Japan. And precipitation as acid as vinegar that falls on Scotland and Scandinavia probably originates in England. How Acidity Is Measured Scientists measure the acidity of rain in pH units. A pH scale from 0 to 14 is used. Depending upon its chemical composition, a solution is either acidic, alkaline (basic), or neutral. Distilled water, which has a pH of 7, is neutral. Substance with pH values less than 7 are acidic, while those over 7 are alkaline. Normal rain water with a pH of 5.6 is slightly acidic. But after reacting with industrial pollutants, particularly sulfur dioxide, the pH of rain quickly drops. When acid rain falls to Earth, much of it ends up in lakes and ponds. In addition to failing directly into a lake, acid rains runs off land into streams and rivers that eventually flow into lakes and ponds. Once acid rain gets into them, its effects can be deadly. Studies started in 1975 in the Adirondacks indicate that salamanders and frogs are the first to die when the pH is lowered. Normally the pH of a lake is 8,0 slightly alkaline. When the pH drops to 7, the eggs of salamanders and frogs fail to hatch. At pH 6.6 snails begin to die. Bacteria that decompose leaf matter die too, and the leaf matter collects on the lake bottom. As the acidity continues to drop, ail the major food chains in the lake become affected. In time all the fish die. Eventually primitive, oxygenconsuming plants nearly choke out all other aquatic greenery. Algae and fungal growth that thrive in an acidic environment move in and cover the entire bottom of the now destroyed lake. Looking like blue vinegar, the lake is now an entirely changed ecosystem. It contains no life expect the fungal and algal growth and a few surfacedwelling water bugs. &n
A.
Y
B.
N
C.
NG
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【单选题】下列学生伤害事故中,学校不承担损害责任的情形是()。
A.
某学生在暑期擅自翻越学校围墙受伤
B.
某小学楼道灯设置不合理,让学生踏空受伤
C.
某学生上课迟到,被班主任要求做200次深蹲运动而诱发哮喘病
D.
某学生上课期间擅自离校,班主任没有及时通知家长,学生在离校期间溺水死亡
【单选题】不适宜应用局部热疗减轻腹痛的情况是
A.
急性胃炎
B.
肠痉挛
C.
消化性溃疡
D.
溃疡性结肠炎
E.
消化性溃疡合并穿孔
【判断题】1930年3月2日,经过中国共产党的建议和筹划,中国左翼作家联盟在上海正式成立。
A.
正确
B.
错误
【简答题】Ein Nachteil von einem Auslandssemester ist es, dass man von Freunden ____ist.
【单选题】不适宜应用局部热疗减轻腹痛的情况是
A.
性胃炎
B.
痉挛
C.
化性溃疡
D.
溃疡性结肠炎
E.
消化性溃疡合并穿孔
【单选题】判断是否具有问题意识,就是可不可以用一个“()”来进行表述。
A.
是什么
B.
为什么
C.
做什么
D.
要什么
【判断题】限售产品指在信息发布前需要取得商品销售的前置审批、凭证经营或授权经营等许可证明,否则不允许发布产品。
A.
正确
B.
错误
【单选题】不适宜应用局部热疗减轻腹痛的情况是
A.
急性胃炎
B.
肠痉挛
C.
溃疡性结肠炎
D.
消化性溃疡合并穿孔
【判断题】限售产品指在信息发布前需要取得商品销售的前置审批、凭证经营或授权经营等许可证明,否则不允许发布产品。
A.
正确
B.
错误
【单选题】下列关于自动变速器的使用,说法错误的是哪个?
A.
换档手柄处于P或N位,ECT内部都处于空档。
B.
换档手柄处于P位时,ECT的输入轴被锁止。
C.
当换档手柄处于D位,车辆行驶时,ECT可从最低档升至最高档。
D.
若车辆前行时,不得将换档手柄拨至R位。
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