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2015考研英语一 · 完形填空
本页为 2015考研英语一 完形填空的完整原文、正确答案与逐题解析（原文约 283 词，共 20 题）。建议先自己作答，再逐题核对解析里的原文定位与干扰项说明。
2015考研英语一完形填空原文
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 that the similar genes seem to be evolving __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.
答案与逐题解析
答案速查
1D
2B
3C
4A
5C
6A
7D
8A
9B
10D
11B
12A
13B
14D
15C
16C
17B
18D
19C
20A
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1第 1 题
答案D
解析原文说朋友共享约1%基因，“That is __ a study... has __”。空格后接研究及其结论，需用what指代前述发现内容，构成“那正是某项研究得出的结论”。what作表语从句引导词，概括整项发现。when/why/how分别表时间、原因、方式，无法指代“共享基因”这一事实本身。
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2第 2 题
答案B
解析空格需与study搭配，表示研究得出上述结论。concluded“得出结论”与前文发现直接对应。defended为辩护，withdrawn为撤回，advised为建议，均与“发表研究成果”语义不符，也无法衔接“共享约1%基因”这一陈述。
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3第 3 题
答案C
解析genome-wide analysis conducted __ 1,932 unique subjects，表示研究在受试者身上进行，介词用on，conducted on为固定搭配。for表目的，with表伴随工具，by表施动者，均不能准确说明分析对象。
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4第 4 题
答案A
解析which __ pairs of unrelated friends and unrelated strangers，研究对朋友对与陌生人对进行对照，compared“比较”符合实验设计。sought寻找、separated分开、connected连接，均未体现“对照分析”的核心动作。
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5第 5 题
答案C
解析The same people were used in both __，同一批人既作朋友样本又作陌生人样本，samples“样本”贴合受试者分组。tests侧重测验，objects物体，examples例子，都不能准确指代基因组分析所用的人群样本。
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6第 6 题
答案A
解析While 1% may seem __，后文“it is not so to a geneticist”形成转折，说明1%在普通人看来微不足道，insignificant“微不足道”最贴切。unexpected意外、unreliable不可靠、incredible难以置信，均与“对遗传学家并非如此”的对比不符。
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7第 7 题
答案D
解析Most people do not even __ their fourth cousins，普通人甚至不认识四代堂亲，know“认识”符合日常经验。visit拜访、miss想念、seek寻找，都无法体现“不知其存在却仍选为友”的反差。
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8第 8 题
答案A
解析select as friends the people who __ our kin，所选朋友在基因上像亲属，resemble“相似”对应前文共享基因。influence影响、favor偏爱、surpass超越，都不能说明朋友与亲属的基因相似性。
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9第 9 题
答案B
解析前文已述共享约1%基因，此处补充嗅觉基因亦共享，also“也”表示递进发现。again重复、instead反而、thus因此，均无法准确连接两项并列的基因发现。
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10第 10 题
答案D
解析Why this similarity exists... is difficult to explain, for now. __ as the team suggests，对原因作推测，Perhaps“也许”引出尚不确定的解释。Meanwhile同时、Furthermore此外、Likewise同样，都缺乏推测语气。
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11第 11 题
答案B
解析there is more __ it，固定搭配more to it，表示“不止于此、另有隐情”。about/from/like均不能构成该习语，也无法衔接后文多种机制共同作用。
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12第 12 题
答案A
解析mechanisms working together that __ us in choosing，这些机制驱使我们选择基因相似的朋友，drive“驱使”符合因果。observe观察、confuse迷惑、limit限制，语义与“促使选择”相反或无关。
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13第 13 题
答案B
解析choosing genetically similar friends __ “functional kinship”，是基因相似而非仅仅功能上的亲缘，rather than“而不是”构成对比。according to依照、regardless of不论、along with连同，都不能体现对“功能亲缘”的否定。
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14第 14 题
答案D
解析functional kinship of being friends with __，与能带来好处的人做朋友，benefits“益处”对应功能亲缘。chances机会、responses反应、missions使命，均无法说明友谊的功能价值。
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15第 15 题
答案C
解析similar genes seem to be evolving __ than other genes，相似基因进化更快，faster对应后文人类进化加速。later更晚、slower更慢、earlier更早，与“进化提速”的方向矛盾。
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16第 16 题
答案C
解析Studying this could help __ why human evolution picked pace，研究有助于理解进化加速原因，understand“理解”最直接。forecast预测、remember记住、express表达，都不能说明探究过去机制的目的。
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17第 17 题
答案B
解析social environment being a major __ factor，社会环境是促进进化的重要因素，contributory“起促成作用的”准确。unpredictable不可预测、controllable可控制、disruptive破坏性，均偏离“推动加速”的含义。
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18第 18 题
答案D
解析explain people’s __ to befriend those of similar，解释人们倾向于结交同类，tendency“倾向”符合行为习惯。endeavor努力、decision决定、arrangement安排，都过于刻意，不如倾向自然。
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19第 19 题
答案C
解析similar __ backgrounds，后文强调欧洲血统同一群体，ethnic“种族/族群”对应血统背景。political政治、religious宗教、economic经济，文中均未作为控制变量提及。
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20第 20 题
答案A
解析care was taken to __ that all subjects... were taken from the same population，采取措施确保受试者来自同一群体，see that为“务必、确保”的习语。show显示、prove证明、tell告诉，都不能表达实验控制中的“保证”之意。
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