When the ALT‐NORM switch on the Audio Control Panel (ACP) is set to ALT:
A.A.The ACP at that station is inoperative and the crewmember cannot communicate on any radios.
B.B.The ACP at that station is inoperative but the crewmember can communicate on one radio.
C.C.The ACP switches to an alternate ACP and all functions operate normally and the crewmember can communicate on all radios
D.D.The ACP switches to standby ACP and all functions operate normally except PA and interphone.
正确答案是B