单项选择题
A.turning ability deteriorates
B.virtual mass increases
C.the effect of the propeller transverse thrust on yaw alters
D.the ship will turn with its head towards the wind
单项选择题 Sometimes lights are（）by fog，haze，dust，smoke，or precipitation which may be present at the light，or between the light and the observer，and which is possibly unknown by the observer.
单项选择题 Pilotage in this country is（）.
单项选择题 Mariners should ensure correct（）of aids to navigation during twilight periods when some lighted aids to navigation are lit while others are not.