新GRE阅读理解36套每日讨论--59（群178674184）

普渡哥

       Biologists have long maintained that two groups of
       pinnipeds, sea lions and walruses, are descended from
       a terrestrial bearlike animal, whereas the remaining
       group, seals, shares an ancestor with weasels. But the
5     recent discovery of detailed similarities in the skeletal
       structure of the flippers in all three groups undermines
       the attempt to explain away superficial resemblance as
       due to convergent evolution—the independent develop-
       ment of similarities between unrelated groups in
10   response to similar environmental pressures. Flippers
      may indeed be a necessary response to aquatic life,
      turtles, whales, and dugongs also have them. But the
      common detailed design found among the pinnipeds
      probably indicates a common ancestor. Moreover,
15   walruses and seals drive themselves through the water
       with thrusts of their hind flippers, but sea lions use
       their front flippers. If anatomical similarity in the
       flippers resulted from similar environmental pressures,
       as posited by the convergent-evolution theory, one
20    would expect walruses and seals, but not seals and sea
       lions, to have similar flippers.
(162 words)


1. The author implies that which of the following was part
of the long-standing view concerning pinnipeds?
□A Pinnipeds are all descended from a terrestrial
bearlike animal.
□B Pinnipeds share a common ancestor with turtles,
whales, and dugongs
□C Similarities among pinnipeds are due to their all
having had to adapt to aquatic life.


2. The author implies which of the following about the
fact that turtles, whales, and dugongs all have flippers?
○A It can be explained by the hypothesis that turtles,
whales, and dugongs are very closely related.
○B It can be explained by the idea of convergent
evolution.
○C It suggests that turtles, whales, and dugongs
evolved in separate parts of the world
○D It undermines the view that turtles, whales, and
dugongs are all descended from terrestrial ancestors.
○E It is the primary difference between turtles, whales,
and dugongs, on the one hand, and pinnipeds, on
the other.


3. Select the sentence in the passage in which the author
shows that the implication of the common view is
contradicted by a new finding.

guijiehao333

C  B  But the common detailed design found among the pinnipeds probably indicates a common ancestor

普渡哥

大家加油做啊！

普渡哥

一楼答对了！

加油！