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Glaciers are a possible source of fresh water that has been overlooked until recently. Three quarters of the Earth’s fresh water supply is still tied up in glacial ice, a reservoir of untapped fresh water so immense that it could sustain all the rivers of the world for 1,000 years. Floating on the oceans are 7,659 trillion metric tons of ice encased in 10,000 icebergs that break away from the polar ice caps, more than ninety percent of them from Antarctic

a.
How much fresh water is tied up in glacial iceA. 75 % of the Earth’s fresh water supply.B. 90% of the Earth’s fresh water supply.C. Enough to support human beings for 1,000 years.D. As much as the water from 10,000 trillion metric tons of ic

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The consequences go far beyond merely the loss of two pieces of property. Each satellite weighed more than half a metric ton and was moving at 7.5 kilometers per second. The resulting explosion was catastrophic (灾难性的), generating a massive cloud of cosmic debris—perhaps 100, 000 pieces of junk bigger than one centimeter in diameter, estimates David Wright, a space expert at the Union of Concerned Scientists. In one stroke, the accident increased by nearly a third the number of stray objects in the crucial 700 - to - 900 - kilometer band known as low Earth orbit (LEO). The junk cloud will eventually disperse around the entire planet, like a shroud(遮蔽物). According to David Wright’s estimation, the explosion of the two satellites may result in

A. 100,000 pieces of junk bigger than one centimeter in diameter.
B. a massive cloud of cosmic debris beyond the low Earth orbit.
C. a cloud of cosmic debris like a shroud around the sun.
D. a third of the number of stray objects in the low Earth orbit.

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Storm - water runoff—also called urban runoff or runoff pollution—is rainwater plus everything else it sucks up after hitting the ground: oil and grease from autos, emissions, brake dust, road salts and pathogens (病原体，致病菌) from animal waste. In many U. S. cities, urban runoff far exceeds industrial waste as the main pollutant in local waterways, says Steve Fleischli, president of the environmental watchdog Water keeper Alliance. The growth of AbTech’s revenues—projected to crack $10 million in 2010—speaks to the growing number of cities eager to address the problem. Storm - water runoff is a mixture of

A. rainwater pills everything it takes away after hitting the ground.
B. oil grease from autos, emissions, brake dust, road salts and animal waste.
C. industrial Waste plus pollutant in local waterways.
D. rainwater plus industrial wast