单项选择题
A.positive
B.negative
C.zero
D.vertical
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? （）
单项选择题 A vessel is heading magnetic north and its magnetic compass indicates a heading of 003°. What action should be taken to remove this error during compass adjustment? （）