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题库 / GMATAdvanced-CR-1
A fossil recently discovered in Marlandia, a chain of islands, proves that a present-day reptile indigenous to Marlandia is descended from an ancient reptile species that lived on the islands millions of years ago. The finding is surprising since the ancestral species was thought to have become extinct when Marlandia was submerged in a global sea-level rise twenty-five million years ago. Based on the new discovery, many scientists have concluded that the sea-level rise in question left at least part of Marlandia unsubmerged.
Which of the following would, if true, provide the most additional support for the scientists' conclusion?
Reptiles in Marlandia have adapted to many environmental changes since the sea-level rise.
Marlandia separated from a much larger landmass about eighty million years ago.
No fossils that prove the relationship between the present-day species and the ancestral species have been found anywhere other than Marlandia.
The present-day reptiles are able to thrive on very tiny Marlandia islands.
The ancestral reptiles could not have survived long at sea.
A 自那些海平面上升以来，M岛的爬行动物已经能够适应很多环境变化。无关
B M岛是8000万年前从更大的陆地分离出来的。无关，讨论的是2500万年前的事。
C 没有发现其他化石，能够证明现在的品种跟它们的祖先之间的联系。无关
D 现在的爬行动物能够生活在M群岛很小的岛上。无关
E 这些爬行动物的祖先不能在海里逗留很久。
因：那次海平面上升至少有部分岛没有被淹没；
（1）攻击结论：它因，其他原因导致祖先物种没有被全部灭绝；（2）攻击前提：无关因果，岛有没有被淹和祖先物种是否灭绝没有因果关系；
E选项取非后，祖先物种可以在海洋中存活很久，即否定了岛被淹和物种灭绝的因果关系。
C选项取非说的是，在其他地方也发现了现代物种和祖先物种关系的化石，这个题干说的感觉挺含糊，也不能说明祖先物种起源其他地方，如果是的话就是部分否定前提了。 总体来讲感觉用取非来排除错误答案还是有点含糊？找对的要高效的多；
评估方向：
证实AB的确有因果关系/抵消中间变量
E加强ab的因果联系。古代爬行动物没有陆地就是活不了。
for E: This shows that reptiles would have to survive at land as it cant survive in sea for sure.
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