单词：heat efficiency of kiln
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Cats and Man Cats struck a bargain with 1 man about 5,000 years ago when he shifted from a nomadic 2 to an agrarian 3 society. As man began to farm, he stored grain. The grain attracted rodents 4 , wh
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This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute. Solar cells convert sunlight to electricity. But they don't take advantage of all that solar heat, thereby missing out on the majority of the solar ene
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HARI SREENIVASAN: As we reported yesterday, the nation's largest egg-producing state, Iowa, has declared a state of emergency following a major outbreak of the avian flu. Millions of chickens and turkeys there and in Wisconsin and Minnesota have been
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In hot countries bricks are often used which have simply been dried in the sun in this way. But these sun-dried bricks will not stand much rain: the water soaks into them, and they once more become lumps of soft clay. 在炎热的地区，以前经常把
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