从下列单词中选择适当的词填空，每个词只能用一次。as other true likely networks include help by last who member friend In traditional societies, everyone in the community is related to everyone else, either as biological relatives or in-laws. In post-industrial societies, this is no longer ______ —we live among strangers, some of whom become friends. As a result, our social circles really consist of two separate ______ —family and friends—with roughly half drawn from each group. Because the pull of kinship（亲属关系） is so strong, we give priority to family, choosing to ______ them in our networks above unrelated individuals. Indeed, people ______ come from large extended families actually have fewer friends. One reason we favor kin is that they are much more ______ to come to our aid when we need ______ than unrelated individuals, even if these are very good friends. Family and friend relationships differ in ______ important ways, too. One is that friendships may not ______ very long if untended. Failure to see ______ for six months or so leaves us less emotionally attached. Family relationships, ______ contrast, are incredibly resilient（能复原的） to neglect. As a result, the family half of our network remains constant throughout most of our lives whereas the friendship component undergoes considerable change over time.