单项选择题
The height of a VHF radio antenna is more important than the power output wattage of the radio because（）.
A.VHF communications are basically line of sight
B.the air is more dense the higher you go
C.salt water is a poor conductor of sound
D.sea water absorbs the radiated energy
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相关考题
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单项选择题
The generators on your rig have shut down，leaving you without navigation lights. Which emergency signal would you transmit over the VHF radio to alert vessels in the area of your predicament? （）
A.Mayday，Mayday，Mayday
B.Pan，Pan，Pan
C.Security，Security，Security
D.Lights out，Lights out，Lights out -
单项选择题
The expression STAND-BY ENGINE means:（）.
A.to get the engine ready
B.to respond to the engine
C.to maneuver the engine
D.to change the engine -
单项选择题
Some goods are missing（）terrible weather.
A.due
B.because of
C.because
D.since
