单项选择题
A.The marine sextant B.Thechronometer C.The magnetic compass D.The gyrocompass
（）means rudder to be held in the force and aft angles.A...
单项选择题（）means rudder to be held in the force and aft angles.
A.Steady B.Meet her C.Midships D.Stop engines
（）means check the swing of the vessel’s head in a turn....
单项选择题（）means check the swing of the vessel’s head in a turn.
1 nautical mile is the lenth of an arc of a great circl...
单项选择题1 nautical mile is the lenth of an arc of a great circle which subtends an angel of（）at the center of the Earth.
A.1degree B.1 minute C.1second D.1.5 degree
