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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
Scientific American(四)月
This is the VOA Special English Development Report. Dye can bring a little color to life. Most clothing is colored with dyes. Modern, manufactured dyes can be costly. Natural dyes from plant and animal products have been used since ancient times. So
VOA慢速英语2008年（十一）月
This is the VOA Special English Development Report. Dye can bring a little color to life. Most clothing is colored with dyes. Modern, manufactured dyes can be costly. Natural dyes from plant and animal products have been used since ancient times. So
VOA慢速英语2007年（五）月
Lesson 35 Getting up Steam 第35课 蒸汽往上冒！ Do you want to know what steam is? Let us get a lump of ice, or a snow-ball, and place it in a saucer in a warm room. It soon melts, and then the saucer is half full of water. If we leave the sau
英国学生科学读本
At one time it was believed that heat was a liquid. Sure, that sounds kind of crazy, but if you think for a second, you might see why. Suppose you have an object thats very hot say a metal spoon thats been sitting in hot coffee. Pick it up and you ca
英语时差8，16
Instead of burning coal, oil, or biomass to heat things up, scientists have found that its possible to use solar energy. For example, some experimental facilities use thousands of mirrors to reflect sunlight onto a large plate on a tower, heating it
英语时差8，16