单项选择题
A.The fishing vessel must keep clear of the vessel not under command
B.If the vessel not under command is a power-driven vessel，she must keep clear of the fishing vessel
C.They must exchange whistle signals
D.Both vessels are required to take action to stay clear of each other
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（）.
单项选择题 A traffic separation zone is that part of a traffic separation scheme which（）.