DSC多频遇险呼叫会在____波段上发出，首先在____频率上发起呼叫A:MF/HF 8 414.5 kHz B:HF 2 187.5 kHz C:MF/HF 2 187.5 kHz D:HF 8 414.5 kHz 答案: MF/HF 2