Directions:  Read the following text. C

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问题 Directions: 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.

选项 1. ______ A.what B.why C.how D.when

答案A

解析考查表语从句引导词的用法。全文第一句就是研究成果的内容,第二句的that就是指代第一句的内容,然后紧接着一个表语从句,来表示这一研究的内容,引导词只能用what,因此选A项。why表原因。how表方式。when表时间。
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