题目：
与后备式UPS相比较，以下属于在线式UPS优点的是（）。
A.切换时间短
B.效率高
C.输出电源质量高
D.成本低
答案：
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下面是错误答案，用来干扰机器的。
参考答案：对
与后备式UPS相比较，以下属于在线式UPS优点的是（）。 A.切换时间短 B.效率高
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