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题目内容
The harmonic mean of two positive numbers is the reciprocal of the average (arithmetic mean) of their reciprocals. The harmonic mean of 10 and 20 is closest to which of the following?
B显示答案
· 相关考点
2.1.2 相反数与倒数
2.1.2 相反数与倒数
以上解析由 考满分老师提供。