More boys than girls are born all over the world, but a new study has found that the closer people live to the equator(赤道), the

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问题     More boys than girls are born all over the world, but a new study has found that the closer people live to the equator(赤道), the smaller the difference becomes. No one knows why.
    The imbalanced sex ratio at birth has been known for more than a hundred years, and researchers have found a large variety of social, economic and biological factors that relate to the sex ratio at birth—war, economic stress, age, diet, selective abortion and more. But latitude(纬度)is a natural phenomenon, unaffected by cultural or economic factors.
    To look at the effect of latitude, Kristen J. Navara of the University of Georgia used the latitude of the capital city in 202 countries, as well as 10 years of data on sex ratio at birth and annual variations in day length and temperature. Dr. Navara performed a statistical analysis which showed that there was a significant relation between sex ratios in favor of boys and latitude. African countries produced the lowest sex ratios—50. 7 percent boys—and European and Asian countries had the highest with 51. 4 percent.
    There are some possible explanations, but none entirely satisfactory. It could be that there is some survival value in producing more girls in warmer regions, but it is unclear what this might be. There may be genetic or racial differences that could explain it, but the connection persists over so many varied populations that this seems unlikely. Mice also produce more male offspring during shorter days or colder weather, but the reasons in these animals are just as mysterious as they are in humans.
    "There’s a possibility that humans might be responding to factors they were programmed to respond to a long time ago—not cultural or socioeconomic, but climate and things like latitude," Dr. Navara said. "What’s interesting is that we may be seeing something that connects us with our animal ancestry. "
What can be learned from the first paragraph?

选项 A、The closer to the equator, the more boys are born.
B、Boys are more used to colder places.
C、Girls have a higher birth rate than boys near the equator.
D、In warmer places the birth ratio between boys and girls is lower.

答案B

解析 此题是一道细节推断题,考查考生根据文章上下文内容进行正确的分析推断的能力。问题问从第一段我们可以了解到什么。第一段指出:世界各地出生的男孩比女孩多。但是一项新的研究发现,人们住得越靠近赤道,其差异就会变得越小。言外之意,在赤道附近男孩女孩出生性别差异比较小,即在远离赤道的地方男孩出生的比例高于女孩,而赤道地区是地球上最热的地区,由此我们可以推断出男孩更能适应比较寒冷的地方。因此,本题的正确答案应该是B。选项A:越靠近赤道,出生的男孩越多,与原文内容不符;C:在赤道附近女孩出生率比男孩出生率要高,原文没有提到;D:在比较温暖的地方男孩和女孩的出生比率都比较低,文章中没有提及。因此这三个选项均为干扰项。
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