单项选择题
A.Only the stern light of the vessel
B.One sidelight and a masthead light of the vessel
C.Only a sidelight of the vessel
D.The masthead lights of the vessel
单项选择题 A vessel is inclined at an angle of loll. In the absence of external forces，the righting arm (GZ) is（）.
单项选择题 A vessel is heading magnetic northwest and its magnetic compass indicates a heading of 317°. What action should be taken to remove this error during compass adjustment? （）
单项选择题 A vessel is heading magnetic northwest and its magnetic compass indicates a heading of 312°. What action should be taken to remove this error during compass adjustment? （）