单项选择题
A towing light is（）.
A.shown at the bow B.white in color C.shown in addition to the sternlight D.an all-round light
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（）.
单项选择题 A signal of intent must be sounded in international waters by（）.
