P: air temperature < optimal body temperature for flight
C: moths are vulnerable to predator
because higher body temperature, large moths are more vulnerable to predator in cool climates than in warm climteas
=> large M are more likely to die in cool climates than in warm climates
=> large M are more common in warm climates than in cool climates( because of the mortality rates difference)
这题逻辑挺简单的，但问题是坑特别大，But后半句跟前面和small moth的比较是无关的，
but之后的句子自成体系，给出了（higher body temperature) 和果____（mortality diffrence in different climate areas)
larger moths can fly faster than smaller ones and hence have a better chance of evading flying predators, but they also have higher optimal body temperatures
这两个分句其实是递进的关系（also），第一个分句意义为大moth比小moth飞得快，更不容易被捕食者捉住，（所以大moth多）。第二句，并且大moth的体温高，从而选B推出大moth在温暖的地方比寒冷的地方要多。（这两句话都要围绕为什么大moth比较多的角度来看，因为also提示是递进的关系）
为什么不选A：A是说大moth的体温高，所以比小moth的飞行机动性强-->不成立，忽略了air temperatures的影响。如果air temperature 低的话，大moth的飞行机动性就会弱，因为大moth的最佳体温高
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发表于 2009-9-10 00:37:00
