单项选择题
A.alternating red and yellow light
B.alternating white and yellow light
C.all-round white or yellow light
D.all-round white light only
单项选择题 A fishing vessel is approaching a vessel not under command. Which statement is TRUE? （）
单项选择题 A facility used for the discharge of a cargo of a particular hazard，such as chlorine，butane or ethane，must have what to warn water traffic of an immediate danger during fire or cargo release?（）
单项选择题 A 20-meter power-driven vessel pushing ahead or towing alongside will display（）.