单词：trace-element
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This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute. Theres a Native American site in Ohio that appeared to be a fort. But recent discoveries by archaeologists at the University of Cincinnati show thats n
Scientific American(九)月
Roughly 1,000 years ago, Europe enjoyed several centuries of balmier average temperatures. Dubbed the Medieval Warm Period, it was the last time before the present that agriculture could flourish in Greenland. This era also provided fodder for countl
Scientific American(十一)月
About 110 million years ago, a large plant-eating dinosaur covered with sharp points walked the land. Called a nodosaur, it is now the best example of its kind ever found. This new species of dinosaur is being called a one-in-a-billion discovery. Rec
2017年VOA慢速英语(五)月
Lake Sediment Could Better Date Ancient Finds Radiocarbon dating is the best-known and most widely used method to determine the age of organic material, such as bone or wood or plant matter. All such material contains radioactive carbon atoms, known
VOA标准英语2012年(十月)
世界本没有长难句，修饰成分多了，便有了长难句。 阅读速度大部分来于短时间内理解长难句的能力。 大家在看长难句的时候，多思考，一个句子为什么这么长，常见的修饰成分到底有哪些？
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