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单选题
ON THE EXTERNAL POWER (EXT PWR) PANEL, WHEN THE "AVAIL" AND ＇NOT IN USE" LIGHTS ARE ILLUMINATED:
A
The Power Ready Relay (PRR) is not energized.
B
A Positive Temperature Coefficient Trip (PTC) has been detected.
C
The external power quality is good, but the network of A/C is fault.
D
The external power quality is good, but not connected to the network.
答案解析
正确答案：D
题目纠错
