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（）.

A.a vessel meeting another head-on
B.a vessel overtaking another in a narrow channel
C.a vessel crossing the course of another
D.the give-way vessel in a crossing situation

单项选择题A sailing vessel shall not impede the safe passage of a（）.

A.power-driven vessel following a traffic lane
B.pilot vessel enroute to a pilot station
C.law enforcement vessel
D.All of the above

单项选择题A sailing vessel is overtaking a power-driven vessel in a narrow channel，so as to pass on the power-driven vessel’s port side. The overtaken vessel will have to move to facilitate passage. The sailing vessel is the（）.

A.stand-on vessel and would sound two short blasts
B.give-way vessel and would sound no whistle signal
C.stand-on vessel and would sound no whistle signal
D.give-way vessel and would sound two prolonged blasts followed by two short blasts

单项选择题A power-driven vessel pushing aheador towing alongside displays navigation lights and（）.

A.two all-round red lights in a vertical line
B.two yellow towing lights in a vertical line
C.two white masthead lights in a vertical line
D.two lights on the stern，one yellow and one white

单项选择题A power-driven vessel leaving a quay or wharf must sound what signal? （）

A.Three short blasts
B.A long blast
C.A prolonged blast
D.No signal is required