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  3. Throughout much of the Tertiary period(most of the past 65 million years), t

Throughout much of the Tertiary period(most of the past 65 million years), t

游客2025-02-19  48
问题     Throughout much of the Tertiary period(most of the past 65 million years), the Arctic supported continuous forests. Only toward the end of that period does the fossil evidence show that certain present-day Arctic plants were established and widely distributed throughout the Arctic. Many Arctic plants are thought to have originated in the high mountain ranges of central Asia and North America, to have spread northward to the Arctic as global temperatures fell in the late Tertiary, and to have achieved a circumpolar distribution by the end of the Tertiary(about 2 million years ago). However, fossil evidence to support these proposals is either lacking or fragmentary. Consequently, the routes by which these plants expanded their ranges during their colonization of the Arctic remain unknown. [br] Which of the following statements about Arctic plants is supported by the passage?
选项 A、The decline in global temperature in the late Tertiary prevented many high-mountain plants from becoming established in the Arctic.
B、There is not enough evidence to firmly establish the historical migration routes of present-day Arctic plants.
C、Present-day Arctic plants are less likely to leave fossil remains than are plants outside the Arctic
答案 B
解析 对应最后两句，not enough对应lacking、fragmentary和remain unknown。A项根据第三句，温度下降使得植物向北极迁移并形成分布，和选项A中的“阻止”相反。C项没有对比北极和北极之外的化石遗迹。
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