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单项选择题

（）电源不能作为安全电压的电源。

A.安全隔离变压器
B.蓄电池
C.自耦变压器

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热门试题

单项选择题电气设备采用安全电压时，电压在（）以上就必须采取直接接触电击的防护措施。

A.24伏以上
B.36伏以上
C.42伏以上

单项选择题Why does the author say that college has never been magical for everyone? ____

A．More high school students go to college than before.
B．Nearly half of the high school students choose to go to college.
C．Few high school graduates end up selling shoes and driving taxis.
D．Many college students don’t fit the pattern of college life.