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  3. It was previously believed that dinosaurs were cold-blooded creatures, like reptiles. However, a recent discovery has lad resear

It was previously believed that dinosaurs were cold-blooded creatures, like reptiles. However, a recent discovery has lad resear

admin2010-04-12  42
问题     It was previously believed that dinosaurs were cold-blooded creatures, like reptiles. However, a recent discovery has lad researchers to believe they may have been warm- blooded. The fossilized remains of a 66 million-year-old dinosaur’s heart were discovered and examined by x-ray. The basis for the analysis that they were warm- blooded is the number of chambers in the heart as well as the existence of a single aorta (主动脉).
    Most reptiles have three chambers in their hearts, although some do have four. But these that have four chambers, such as the crocodile, have two arteries (动脉) to mix the oxygen-heavy blood with oxygen-lean blood. Reptiles are cold-blooded, meaning that they are dependent on the environment for body heat. Yet the fossilized heart had four chambers in the heart as well as a single aorta. The single aorta means that the oxygen-rich blood was completely separated from the oxygen-poor blood and sent through the aorta to all parts of the body.
    Mammals, on the other hand, me warm-blooded, meaning that they generate their own body heat end are thus mere tolerant of temperature extremes. Birds and mammals, because they are warm blooded, move more swiftly and have greater physical endurance than reptiles.
    Scientists believe that the evidence now points to the idea that all dinosaurs were actually warm- blooded. Ironically, the particular dinosaur in which the discovery was made was a Tescelosaurus, which translates to "marvelous lizard." A lizard, of course, is a reptile.
The author implies that reptiles ______.
选项 A、have four-chambered hearts
B、have one aorta
C、are cold-blooded
D、are faster and have more endurance than mammals
答案C
解析 根据文章第二段第三句话“Reptiles are cold-blooded，meaning that they are dependent on the environment for body heat．”爬行动物是冷血动物，这意味着它们要依赖环境来升高体温。所以C正确。
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