2. 外语
  3. Many researchers attribute the large number of physiological and behavioral similarities between birds and mammals, which have s

Many researchers attribute the large number of physiological and behavioral similarities between birds and mammals, which have s

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问题 Many researchers attribute the large number of physiological and behavioral similarities between birds and mammals, which have separate evolutionary histories, to endothermy (a thermoregulatory strategy whereby warm body temperature is maintained through internal heat sources). However, Farmer argues that parental care rather than endothermy is the key to understanding the similarities between mammals and birds. According to Farmer, while endothermy provides an explanation for a few similarities, such as the presence of body insulation, endothermy is just one characteristic among many related to parental care. The two purported advantages of endothermy that have been most frequently cited by researchers are an expanded range of inhabitable environments and the ability to sustain vigorous exercise. But metabolism has to increase substantially (at great energy cost) therefore conferring any significant thermoregulatory advantage in terms of the former, and there is no causal biological linkage to explain why endothermy would be essential to sustain exercise. Farmer argues instead that endothermy evolved as a means to control incubation temperature and that the ability to sustain exercise evolved separately, as a means to improve a parent’s ability to forage and provision its young.
The primary purpose of the passage is to
选项 A、present a scientific theory that challenges a widely held theory
B、summarize the basis for a large body of scientific research
C、defend an established scientific theory in light of recent criticism
D、express skepticism about the results obtained by a particular researcher
E、compare the results of two particular scientific studies
答案A
解析 a widely held theory指代第一句话many researchers认为体温调控解释相似性的观点。scientific theory指代Farmer的父母呵护主要解释相似性的观点。challenge可以从第二句的However中反映出来。
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