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Polar-ice meltdown
Some scientists warn that ice near the Earths Poles may indeed be melting. This polar meltdown may be the first sign that the Earth is heating up. We could be in very serious trouble if this trend continues. It is estimated that a meltdown of as little as 10 percent of Antarcticas ice would raise sea levels around the globe by 4 to 9 meters. Floods would cover low-lying regions and turn coastal cities like New York and New Orleans into real life underwater world.
Scientists first predicted in the 1970s that heat trapped in the Earths atmosphere could cause a polar meltdown. Many now believe that human activities are turning up the heat. When we burn fossil fuels like coal and oil, we add carbon dioxide(CO2) gas to the Earths atmosphere. Cutting down trees also makes CO2 levels raise because trees normally soak up CO2 to make food. Scientists say higher CO2 levels strengthen the greenhouse effect and could increase the Earths temperature. In fact, CO2 levels have risen by 30 percent since the Industrial Revolution of the 18th and 19th centuries.
Over the past three years, satellite measurements have shown a sea level rise of about a quarter inch worldwide. If nothing is done to reduce fossil-fuel pollution and global warming, sea levels will rise even more. says geologist Richard Alley.
But even Alley admits that a polar meltdown would take time. The ice in Antarctica and Arctic locks up nearly nine times the volume of water contained in all the worlds rivers and lakes. These are such big ice cubes and it would probably take thousands of years to melt them.
Another scientist Charles Bentley doesnt think a meltdown will happen at all. Even if warmer temperatures begin to melt polar-ice, he says, the excess moisture would most likely be redeposit as snow. In other words, the melted ice would evaporate into the atmosphere, refreeze, and fall as rain and snow over the Poles.
1. What consequence of global warming is mentioned in the passage?
A. More tropical storms. B. More tropical diseases.
C. Changes in farm productivity. D. Coastal flooding.
2. Which of the following statements does the second paragraph support?
A. CO2 in the atmosphere cannot keep the heat from escaping into space.
B. The increase of CO2 gas may warm the planet and help to melt polar ice.
C. Cutting down trees helps to greatly reduce CO2 levels.
D. The end of the short-lived age of fossil fuels is already in sight.
3. Geologist Richard Alley most likely agrees that _______.
A. the sea-level rise can be prevented by cutting back on energy-consuming activities
B. the recent breaking off of ice blocks from Antarctica is just a natural part of a long-term cycle
C. Antarctica temperatures have significantly changed since the Industrial Revolution
D. the polar meltdown may be an accidental change of climate rather than a sign of global warming
4. Charles Bentley believes that a polar meltdown will not occur because _______.
A. governments around the world are beginning to reduce CO2 levels in the air
B. a melting of the polar ice cannot be achieved with the present technologies
C. the melted ice in the polar areas would change into snow and rain over the Poles
D. the suns heat would have no chance of being absorbed by the polar ice
5. In which paragraph does the author mention the immense quantities of polar ice?
A. In the second paragraph. B. In the third paragraph.
C. In the fourth paragraph. D. In the fifth paragraph.
【答案与剖析】本文就极地冰雪熔化的究竟停止了切磋,首要说了然极地冰雪熔化的启事及风险,文章最后一段也简述了极地冰雪熔化不会对地球产生影响。
1. D。细节题。环球气温降低酿成的结果是:从 Floods would cover low-lying regions and turn coastal cities可知答案选D。
2. B。概括题。第2段首要讲了一些报酬的活动(如CO2 增加)会致负气温的降低,故可知答案为B。
3. A。推理题。从 If nothing is done to reduce fossil-fuel pollution and global warming, sea levels will rise even more(如果不采纳办法减少污染警惕的话,环球气温降低会导致海平面上升)也就是说如果减少一些动力耗损能够对海平面上升有所按捺,故答案选A。
4. C。细节题。从 the melted ice would evaporate into the atmosphere, refreeze, and fall as rain and snow over the Poles可知答案选C。
5. C。判定题。从第4段 The ice in Antarctica and Arctic locks up nearly nine times the volume of water contained in all the worlds rivers and lakes. These are such big ice cubes 可知答案为C。
2017成都小升初招生政策、报名时间、对口中学、艺体特长生的录取、重点民办中学的小升
2016杭州小升初预热,本篇笔者带来杭州小升初,涵盖杭州各城区入学政策、招考资讯、择