单项选择题
A towing light is（）.
A.shown below the sternlight B.white in color C.displayed at the masthead D.a yellow light having the same characteristics as the stern light
单项选择题 A towing light is（）.
单项选择题 A towing light（）.
单项选择题 A signal of one prolonged，one short，one prolonged，and one short blast，in that order is given by a vessel（）.
