A mark or place at which a vessel comes under obligatory entry，transit，or escort procedure is know as（）.

You are making a telephone call ship-to-shore using the VHF-FM service.You can tell that the working channel is busy if you hear（）.

There is a drifting mine（）in position 21 degrees 31 minutes North 124 degrees 20 minutes East.

Please（）all the lines fore and aft，the vessel is just in her position of the berth now.

A call between any two ship stations on an intership working frequency shall have a maximum duration of（）.

If it（）fine tomorrow，we shall start unloading.

Should that kind of weather（），the two ships would touch each other.

How should the letter O be pronounced when spoken on the radiotelephone?（）

（）your present speed?

The height of a VHF radio antenna is more important than the power output wattage of the radio because（）.