Fossils of the coral Acrocora palmata that date from the last period when glacie

游客2024-01-13  7

问题 Fossils of the coral Acrocora palmata that date from the last period when glaciers grew and consequently spread from the polar regions are found at ocean depths far greater than those at which A. palmata can now survive. Therefore, although the fossilized A. palmata appears indistinguishable from A. palmata now living, it must have differed in important respects to have been able to live in deep water. The argument depends on the assumption that

选项 A、no fossils of the coral A. palmata have been found that date from periods when glaciers were not spreading from the polar regions.
B、geological disturbances since the last period during which glaciers spread have caused no major downward shift in the location of A. palmata fossils.
C、A. palmata now live in shallow waters in most of the same geographical regions as those in which deep-lying A. palmata fossils have been found.
D、A. patlmata fossils have been found that date from each of the periods during which glaciers are known to have spread from the polar region.
E、A. palmata can live at greater depths where the ocean temperature is colder than they can where the ocean temperature is warmer.

答案 B

解析 本题仅根据冰川形成期的Acrocora palmata珊瑚化石的位置比它们现在生长的地方深,就做出了冰川形成期的Acrocora palmata珊瑚与今天的Acrocora palmata珊瑚在许多重要的方面有很大不同的结论。要使结论成立,就要对结论的前提中所提及的“深”做进一步的限制。本题的5个选项中,只有(B)表明化石的位置较深不是由他因引起的,从而就可合理地推出冰川时期paclmata珊瑚实际生活的区域与它们的化石形成的区域基本上一致,这样才能使本题论证中的结论合理地推出,由此分析可知(B)为正确答案;(A)为无关选项;(C)、(D)和(E)都不能从本题的论证中合理地推出。
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