How does a coast radio station communicating by HF radio normally identify itself?（）

A.Point the horn down
B.Turn cylinder upside-down
C.Break the rupture disc
D.Pull pin，squeeze grip

A.This requires extensive calculation and is usually performed only by a naval architect not by a ship's officer
B.Determine the point where aground and the draft at that point，then calculate it using the grounding formula
C.Use the hydrostatic tables and enter with the mean draft before grounding and the mean draft after grounding
D.Use the inclining experiment formula and substitute the change of trim for the angle of list

A.The further forward and closer to amidships the more readily the tug will trip
B.Placement further aft permits more effective pulling，better steering and eliminates the danger of tripping
C.Installing the bitts down low lowers the center of gravity
D.The height and position of towing bitts has no significance