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Scrap-Metal Separation May Become Cheaper 新技术降低废金属分离成本 According to the Environmental Protection Agency, the United States throws 14.8 million tons of scrap metal into landfills every year. One of the main reasons is the diffi
VOA标准英语2015年(二月)
Bladeless Wind Generator Safe for Birds Wind turbines are tall structures with large blades used to produce electricity. They are useful sources of low-cost, renewable energy. But they can also be deadly to birds and bats. The turbines large blades t
2015年VOA慢速英语(七)月
AS IT IS 2015-03-25 Scrap Metal Separation May Become Less Costly 废金属分离技术成本可能会降低 Recycling, or re-using, metals is much less costly than making them from raw materials in the Earth, called ore. But when old cars, household
2015年VOA慢速英语(三)月
Radiation causes damage at the most fundamental level. It mutates the blueprint of life, DNA. Earth's magnetosphere is our crucial defense. It's so fundamental to our evolution and continued existence that the race is on to understand why it's changi
自然百科2011年
Easily confused by this idea, there has a big thawed iron inner core, so that I think it's just the bar magnet, just permanent magnet frozen in nad, and that's where causes all the magnetic field. But it's too hot inside the Earth, that can't happen
自然百科2011年