单项选择题
A.are not the same color as either side light
B.have a lesser range of visibility than the prescribed lights
C.do not impair the visibility or distinctive character of the prescribed lights
D.All of the above
单项选择题 A vessel is underway with a work stage rigged over the side. A seaman may work on the stage，but only when（）.
单项选择题 A vessel is to make a voyage between New York and San Juan，Puerto Rico，and return. The crew should be signed on（）.
单项选择题 A vessel is overtaking when she can see which light(s) of a vessel ahead?（）