Read the following text. Choose the best word(s) for each numbered blank and mark A, B, C or D on ANSWER SHEET 1. (10 points)
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 1932 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. The team also controlled the data to check ancestry of subjects.
20． ______
考查动词词义辨析。see that是固定搭配，意为“务必，保证”，另外三个选项都不能与that构成固定搭配，所以均表达本身的意思。本句话的意思是：尽管所有的受访者都拥有欧洲血统，（研究者们）也花心思保证了所有（用于比对的）朋友和陌生人也都来自同一群种。因此A项符合题意。show展示。prove证明。tell辨别。
