“2017年GRE阅读每日长难句解析”由出国留学网GRE考试栏目精心为广大考生整理，希望可以帮助到大家，小编在这里祝大家考试顺利! This preference for exogamy，Gutman suggests， may have derived from　West African rules governing marriage，which，though they differed from one tribal group to another，all involved some ...