考博英語真題

2015考研英語真題完整版（英語一）
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　　Though not biologically related, friends are as “related” as fourth cousins, sharing about 1% of genes. That is _(1)_a study, published from the University of California and Yale University in the Proceedings of the National Academy of Sciences, has__(2)_.
　　The study is a genome-wide analysis conducted _(3)__1,932 unique subjects which __(4)__pairs of unrelated friends and unrelated strangers. The same people were used in both_(5)_.
　　While 1% may seem_(6)_,it is not so to a geneticist. As James Fowler, professor of medical genetics at UC San Diego, says, “Most people do not even _(7)_their fourth cousins but somehow manage to select as friends the people who_(8)_our kin.”
　　The study_(9)_found that the genes for smell were something shared in friends but not genes for immunity .Why this similarity exists in smell genes is difficult to explain, for now,_(10)_,as the team suggests, it draws us to similar environments but there is more_(11)_it. There could be many mechanisms working together that _(12)_us in choosing genetically similar friends_(13)_”functional Kinship” of being friends with_(14)_!
　　One of the remarkable findings of the study was the similar genes seem to be evolution_(15)_than other genes Studying this could help_(16)_why human evolution picked pace in the last 30,000 years, with social environment being a major_(17)_factor.
　　The findings do not simply explain people’s_(18)_to befriend those of similar_(19)_backgrounds, say the researchers. Though all the subjects were drawn from a population of European extraction, care was taken to_(20)_that all subjects, friends and strangers, were taken from the same population.