托福阅读真题+题目+答案：The Origins of the Arctic Fox

托福阅读真题+题目+答案：The Origins of the Arctic Fox

The arctic fox lives in the far northern Arctic region with other well-known arctic animals like the caribou, musk ox, and polar bear.Scientists aren't sure exactly when the arctic fox first evolved. Arctic fox bone fragments from the Pleistocene epoch (2.6 million-11,700 years ago) are rare, and the ones that do exist are difficult to date with any degree of accuracy. The oldest confirmed arctic fox bone is believed to be 200,000 years old. There are other bones that may be 400,000 years old, but whether they belonged to an arctic fox or some other fox remains under debate. "It's still an open question,"says Love Dalen,a Swedish biologist who has been using genetics in an attempt to understand the evolution of the arctic fox. "Right now the best estimate is that arctic foxes emerged somewhere between 200,000 and 400,000 years ago, presumably during one of the ice Ages."

1.According to paragraph 1, which of the following do scientists now believe about the arctic fox?

O It emerged at about the same time as the caribou, musk ox, and polar bear.

O It left a large number of bone fragments during the Pleistocene epoch.

O It has been in existence for at least 200,000 years.

O It probably could not survive during any of the Ice Ages.

2.According to paragraph 1, all of the following are reasons why scientists do not know when the arctic fox first appeared EXCEPT:

O Remains of the arctic fox are difficult to date accurately.

O The oldest fox bones may be those of other species of fox.

O Ancient bones from the arctic fox are not found very often.

O Most signs of the original arctic fox were destroyed during the Ice Ages.

For many years researchers believed the species arose in Europe,basing this conclusion on the location of those 2000-year-old fossils. Since the early 1980s, however, genetic comparisons between different fox species have revealed some surprising results. For example, research done by Robert Wayne at the University of California at Los Angeles has found that the arctic fox, despite its unique appearance and adaptations, is actually much more closely related to other foxes than had previously been thought. Its closest living relative, according to the genetic studies, is the North American swift fox.

3.According to paragraph 2, the belief that the arctic fox arose in Europe is called into question by

O the location where the oldest confirmed arctic fox bones have been discovered

O the arctic fox's unique appearance and adaptations

O the fact that the arctic fox differs greatly in genetic makeup from other fox species

O the fact that the closest living relative of the arctic fox is a North American fox

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