Fossil hunters have unearthed fragments of leg bone belonging to a giant camel that lived in the forests of the High Arctic more than three million years ago. The ancient beast stood almost three meters tall at the hump, about a third higher than its modern descendant, the single-humpeddromedary(单峰驼), or Arabian camel. Scientists who found the remains said the extinct mammal may have already had the wide, flat feet and fatty hump associated with adaptation to life in the desert, because they could have helped the animal endure its harsh, snow- covered habitat.Remnants of the oversizedungulate(有蹄类动物), 30 pieces in all, were recovered from a steep, sandy slope on Ellesmere island, the most northern and mountainous of the Canadian Arcticarchipelago(群岛). The sediments around the fossils date to at least 3.4 million years old, when the region was much warmer than today and dominated bylarch(落叶松) forests. Temperatures hovered a few degrees below zero, and winters plunged the region into six months of darkness.Fossils from previous expeditions have shown that the camel"s ancestors originated in North America 45 million years ago, and crossed the Bering Strait into China and Eurasia more than 7 million years ago. In 1913, the first giant camel remains were uncovered in Yukon, about 1200km south of the Fyles Leaf Bed. "This is the first evidence of camels in the High Arctic," said Mike Buckley, a researcher at Manchester University who studied the remains.The frigid conditions on Ellesmere island preserved connective tissue calledcollagen(胶原蛋白) in the specimens. When Buckley compared the chemical makeup of the collagen with tissue from the Yukon camels, he found they were closely related, and possibly the same species. They also matched modern dromedaries, but not the twin-humped Bactrian camel. The study appears in the journal,Nature Communications. "This ancestor of modern camels may already have had some of the adaptations that helped it survive in harsh climates—the hump for fat storage for instance. The large flat feet were ideal for soft ground, so it didn"t sink through sand or snow. The large eyes perhaps helped with poor visibility in the long, dark winters," said Buckley.No other mammal remains have been unearthed at Fyles Leaf Bed, but at a nearby site, expeditions uncovered fossilized remnants from a beaver, a three-toed horse and a badger, that lived at the same time. "We now have a new fossil record to better understand camel evolution," said Natalia Rybczynski, at the Canadian Museum of Nature in Ontario. "Perhaps some specializations seen in modern camels, such as their wide flat feet, large eyes and humps for fat may be adaptations derived from living in a polar environment."
A．The ancient giant camel is able to adapt quickly.B．The ancient giant camel and the modern Yukon camels could be relatives.C．The modern camels have a better ability to adapt to the environment.D．The hash climates of the Arctic forced animals to store fat to survive.
点击查看答案
设系统的开环传递函数没有右平面的零点和极点，且开环渐进对数幅频特性曲线为下图中的L0加入串联校正环节后的开环渐进对数幅频特性曲线为图中的L1求校正环节的传递函数，画出该环节的伯德图（对数幅频特性曲线用渐进线表示），并说明该校正环节的作用
设系统的开环传递函数没有右平面的零点和极点，且开环渐进对数幅频特性曲线为下图中的L0加入串联校正环节后的开环渐进对数幅频特性曲线为图中的L1求校正环节的传递函数，画出该环节的伯德图（对数幅频特性曲线用渐进线表示），并说明该校正环节的作用
点击查看答案
某大型商业综合体，属于消防安全重点单位，关于该商业综合体内消防安全重点部位的确定，做法错误的是( )。
A.应将地下二层、三层的汽车库确定为消防安全重点部位 B.应将地上一至三层的商城营业厅确定为消防安全重点部位 C.应将地上八层的美容院确定为消防安全重点部位 D.应将消防控制室确定为消防安全重点部位
点击查看答案
题目内容
（请给出正确答案）
参考答案
十点题库官方参考答案
（由十点题库聘请的专业题库老师提供的解答）
