标题: 求教 tpo45阅读第一篇第四题 [打印本页] 作者: 温润的风 时间: 2016-6-17 12:05 标题: 求教 tpo45阅读第一篇第四题 The purpose of paragraph 3 is to
A contrast today's Beringian landscape with other landscapes in the American continent
B describe the Beringian landscape during the last ice age
C explain why so many Beringian species became extinct during the last ice age
D summarize the information about Beringia that historians agree on
原文
The presence of mammal species that require grassland vegetation has led Arctic biologist Dale Guthrie to argue that while cold and dry, there must have been broad areas of dense vegetation to support herds of mammoth, horse, and bison. Further, nearly all of the ice-age fauna had teeth that indicate an adaptation to grasses and sedges; they could not have been supported by a modern flora of mosses and lichens. Guthrie has also demonstrated that the landscape must have been subject to intense and continuous winds, especially in winter. He makes this argument based on the anatomy of horse and bison, which do not have the ability to search for food through deep snow cover. They need landscapes with strong winds that remove the winter snows, exposing the dry grasses beneath. Guthrie applied the term "mammoth steppe" to characterize this landscape.