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.
8选？
上下文语义衔接+动词辨析空格处要求填入一个及物动词，能够直接接宾语kin（亲戚），然而四个选项都是及物动词，所以关键在于判断哪个更符合上下文语境。空所在的语境为：大多数人甚至不认识他们隔三代的表亲，但却设法选择那些____他们亲戚的人作为朋友。将四个选项分别代入，B选项“影响他们的亲戚”，C“支持他们的亲戚”，D选项“超过他们的亲戚”均无上下文依据，根据全文中心导向：基因上的相似性，不难判断，A选项“像他们亲戚”符合上下文语义，故答案为A。
