单项选择题
An occulting light is one in which（）.
A.the period of darkness exceeds the period of light B.there is only a partial eclipse of the light C.the periods of light and darkness are equal D.the period of light exceeds the period of darkness
单项选择题 An inconspicuous，partly submerged vessel or object being towed，where the length of tow is 100 meters，shall show（）.
单项选择题 An all-round flashing yellow light may be exhibited by a(n)（）.
单项选择题 All fog signals shall be sounded every two minutes with the exception of a vessel（）.
