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  3. Hitherto, there is no evidence yet that would definitively prove whet

Hitherto, there is no evidence yet that would definitively prove whet

游客2024-01-11  69
问题            Hitherto, there is no evidence yet that would definitively prove whether or
       not some dinosaurs were warm-blooded, but scientists have begun to investigate
       oxygen isotopic abundances in the annual growth bands of teeth or bones of high
Line    latitude, hence seasonally influenced, terrestrial dinosaurs. The ratio of oxygen
(5)     isotopes depends on temperature, and an absence of seasonal variations in
       oxygen 18—a heavy version of the common oxygen 16 atom-would strongly
       suggest that the animals maintained a constant internal temperatures. Such a
       finding would not, however, constitute "proof" that dinosaurs were warm
       blooded, as there are external mechanisms that cold-blooded animals employ to
(10)    regulate body temperatures and thereby influence metabolic rates. More
       nettlesome is that proof would have to come from discovery of intact dinosaur
       remains in which the soft tissue had not been replaced or altered, and from
       which the biomolecules responsible for thermoregulation could be extracted,
       identified and characterized. Such a proof is unlikely, as it would require an
(15)    almost impossible level of preservation over 65 million years, plus the advent of
       biotechnology that does not yet exist. [br] The author’s primary purpose is to
选项 A、answer a theoretical question in the field of dinosaur thermoregulation
B、discuss the current state of research in the field of dinosaur thermoregulation
C、resolve a dispute in the field of dinosaur thermoregulation research
D、predict a future crisis in the field of dinosaur thermoregulation research
E、suggest some of the possible benefits of a technique in dinosaur thermoregulation research
答案 B
解析
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