A. 后背 B. 定焦镜头 C. 取景器 D. 变焦镜头
A. EPIRB's that transmit on 406 MHz B. Survival craft VHF transceivers that provide a beacon on 121.5 MHz COSPAS-SARSAT EPIRBs D. SARTs operating on 9 GHz
A. 正确 B. 错误