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Every winter some twenty million tons of salt are dumped on America's road.That sodium chloride melts the ice, so it prevents its formatin, helping to prevent accidents. But road salt has its downside. This is not very economical because salt is main
2016年Scientific American(一)月
This week on Why Tell Me Why, we are finding out why the oceans are so salty. So the oceans are salty because the oceans have been around, lets say, for over five hundred million years. And over the course of time what we found out is that weve alway
自然百科2009年
On its website, a history of the company makes no mention of leador indeed of Thomas Midgleybut simply refers to the original product as containing a certain combination of chemicals. 在它的网站上，公司的历史没有提及铅──也没有提
万物简史
By counting back through these layers and measuring the amount of lead in each, he could work out global lead concentrations at any time for hundreds, or even thousands, of years. The notion became the foundation of ice core studies, on which much mo
万物简史
Lead is a neurotoxin. Get too much of it and you can irreparably damage the brain and central nervous system. Among the many symptoms associated with overexposure are blindness, insomnia, kidney failure, hearing loss, cancer, palsies, and convulsions
万物简史
If you were going to a restaurant and wanted a healthier option, 如果你去饭店，你想吃得健康一点， which would you choose, grilled or fried chicken? 你会选择哪种食品呢，烤鸡还是炸鸡？ Now most people would answer grill
TED演讲教育篇