水冷壁发生结焦后，炉膛内温度会下降。
A. 对
B. 错
What is meant by the term " radio silence "?
A. Stations remaining off the air to safeguard proprietary information.
B. Two three-minute silent periods, at the top and bottom of every hour, that provide a transmitting " window " for distressed vessels to transmit distress alerts.
C. Stations not directly involved with the on-going distress communications may not transmit on the distress frequency or channel.
D. Communications on a distress frequency or channel is banned for 24 hours following the cessation of the distress traffic.
What frequency is required in survival craft portable radiotelephony equipment?
A. 121.5 MHz.
B. 156, 3 MHz.
C. 156. 650 MHz.
D. 156. 8 MHz.
Of the following, which system provides the highest degree of detection probability and location accuracy?
A. 2, 182 kHz Radiotelephone Automatic Alarm Generator.
B. 406 MHZ EPIRBs.
C. 122.5 MHz EPIRBs.
D. 156. 252 MHZ EPIRBS.
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