A、have reserves of powerB、have other electric reservesC、ensure the steady flow

游客2024-03-08  4

问题

选项 A、have reserves of power
B、have other electric reserves
C、ensure the steady flow of electricity
D、ensure the operation of generators

答案 B

解析 从原文该句可以知道为了维持60赫兹的交流电频率,PJM Interconnection必须have other electrical reserves,因此,本题应选B。
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