2. 外语
  3. A、have reserves of power B、have other electric reserves C、ensure the steady flow of electricity D、ensure the operation of genera

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

admin2021-09-17  20
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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大学英语六级

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