According to the United Nations, an aging society refers to one ____ 10 percent or more of the population is over 60, or 7 percent or more is over 65.A.whereB.whenC.whichD.that
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A解析这题考查定语从句的用法，先行词是one代指an aging society“一个老龄化社会”，定语从句中不缺主语，宾语，表语，所以填where。