24. Most land-dwelling vertebrates have rotating limbs terminating in digits, a characteristic useful for land movement. Biologists who assume that this characteristic evolved only after animals abandoned aquatic environments must consider the Acanthostega, a newly discovered ancestor of all land vertebrates. It possessed rotating limbs terminating in digits, but its skeleton was too feeble for land movement. It also breathed using only internal gills, indicating that it and its predecessors were exclusively aquatic. The statements above, if true, most strongly support which one of the following? (A) Many anatomical characteristics common to most land animals represent a disadvantage for survival underwater. (B) None of the anatomical characteristics common to most aquatic animals represent an advantage for survival on land. (C) Acanthostega originated as a land-dwelling species; but evolved gills only after moving to an underwater environment. (D) All anatomical characteristics not useful for land movement but common to most land animals represent an advantage for survival underwater. (E) Certain anatomical characteristics common to some aquatic animals represent an advantage for survival on land.
这里讨论的是a newly discovered ancestor of all land vertebrates。根据全文的意思是说水里的动物具备在陆地上生存的特点。but its skeleton was too feeble for land movement. It also breathed using only internal gills, indicating that it and its predecessors were exclusively aquatic.这句话说明Acanthostega是水里德动物。 所以E对、
是不是因为文中没有提到过anatomical characteristics not useful for land movement but common to most land animals? 该是无关内容吧？ 而E中的certain anatomical characteristics common to some aquatic animals 文中有提到，而且一般都该是从水生往陆生脊椎动物进化吧？
以下是引用mariezhu在2003-11-25 13:01:00的发言： 是不是因为文中没有提到过anatomical characteristics not useful for land movement but common to most land animals? 该是无关内容吧？ 而E中的certain anatomical characteristics common to some aquatic animals 文中有提到，而且一般都该是从水生往陆生脊椎动物进化吧？
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发表于 2003-11-25 02:51:00
