标题: LSAT 黄皮书下册SET 5 SECTION3 Q21 [打印本页] 作者: mythicalman 时间: 2003-11-16 16:39 标题: LSAT 黄皮书下册SET 5 SECTION3 Q21 21. Even the earliest known species of land animals, known from fossils dating from the late Silurian period 400 million years age show highly evolved adaptations to life on land. Since neither aquatic nor amphibious animals exhibit these adaptations, early species of land animals must have evolved very rapidly after leaving an aquatic environment.
Which one of the following is an assumption on which the argument depends?
(A) Known fossils of early land animals include fossils of animals that lived relatively soon after the first emergence of land animals
(B) Fossils from the late Silurian period represent only a small number of the animal species that were alive at that time
(C) No plants were established on land before the late Silurian period.
(D) No present-day species of aquatic animal is descended from a species of animal that once lived on land
(E) All animals alive in the late Silurian period lived either exclusively on land or exclusively in the water.
B 为什么选B，谁能分析分析作者: Marrow 时间: 2003-11-16 16:51
答案是a.结论是这种动物立马就变的跟水里长的不一样了。原文关于立马没有说明白，所以要加个立马的假设--a.所发现的确实是最早一批的陆生动物。作者: cranberry 时间: 2003-11-16 16:53
我也不能理解为什么选B！我倾向于选A，因为对B取非无法否定结论。作者: mythicalman 时间: 2003-11-17 00:02
各位老大，又复核了一下，是A。不好意思，摆了个乌龙。作者: 番茄炒蛋 时间: 2003-11-17 00:05
have evolved very rapidly 我还是认为选B更好，上面的那句话表明 如果represent only a small number of the animal species ，那么就表明那个时候有非常多的这种动物，也正好符合了have evolved very rapidly
fossils of early land animals include fossils of animals that lived relatively soon after the first emergence of land animals 而这句话并不能表达陆地动物数量增长很快的逻辑关系
这题想了挺久，就是不知道对不对了 我原来做题的时候是选对了，当初好像选B的时候好像就是这样想的 作者: mindfree 时间: 2003-11-17 02:06
A.
There is a obvious gap: "earliest known species" and "early species of land animals".
A filled the gap.作者: 番茄炒蛋 时间: 2003-11-19 01:35
总教头说的很棒，从技术角度来做这题，只要找到这个GAP就可以了 但是这两个是不是一批货和进化的快慢有什么关系呢 还是有疑问