黃金閱讀 34 EXTINCTION OF THE DINOSAURS - 英檢

有幾題看了解答還是不解, 麻煩高手指點一下..
這兩題其實我都猜對了, 但我想破頭還是不解為何....

Paragraph 3 If true, though, why did cold-blooded animals such as snakes,
lizards, turtles, and crocodiles survive the freezing winters and torrid
summers? These animals are at the mercy of the climate to maintain a livable
body temperature. It's hard to understand why they would not be affected,
whereas dinosaurs were left too crippled to cope, especially if, as some
scientists believe, dinosaurs were warm-blooded. Critics also point out that
the shallow seaways had retreated from and advanced on the continents
numerous times during the Mesozoic, so why did the dinosaurs survive the
climatic changes associated with the earlier fluctuations but not with this
one? Although initially appealing, the hypothesis of a simple climatic change
related to sea levels is insufficient to explain all the data.

3. Why does the author mention the survival of "snakes, lizards, turtles, and
crocodiles" in paragraph 3?
○To argue that dinosaurs may have become extinct because they were not
cold-blooded animals
○To question the adequacy of the hypothesis that climatic change related to
sea levels caused the extinction of the dinosaurs(正解)
○To present examples of animals that could maintain a livable body temperature
more easily than dinosaurs
○To support a hypothesis that these animals were not as sensitive to climate
changes in the Cretaceous period as they are today


Paragraph 5 lr has not been common at Earth's since the very beginning of the
planet's history. Because it usually exists in a metallic state, it was
preferentially incorporated in Earth's core as the planet cooled and
consolidated. lr is found in high concentrations in some meteorites, in which
the solar system's original chemical composition is preserved. Even today,
microscopic meteorites continually bombard Earth, falling on both land and sea.
By measuring how many of these meteorites fall to Earth over a given period of
time, scientists can estimate how long it might have taken to deposit the
observed amount of lr in the boundary clay. These calculations suggest that a
period of about one million years would have been required. However, other
reliable evidence suggests that the deposition of the boundary clay could not
have taken one million years. So the unusually high concentration of lr seems
to require a special explanation.

10. Paragraph 5 implies that a special explanation of lr in the boundary clay
is needed because

○the lr in microscopic meteorites reaching Earth during the Cretaceous period
would have been incorporated into Earth's core
○the lr in the boundary clay was deposited much more than a million years ago
○the concentration of lr in the boundary clay is higher than in microscopic
meteorites
○the amount of lr in the boundary clay is too great to have come from
microscopic meteorites during the time the boundary clay was deposited(正解)


感激不盡...


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