（）is the most visible signal of distress from a lifeboat at sea in the daytime.

单项选择题Which signal is recognized as a distress signal?（）.

A.Directing the beam of a searchlight at another vessel
B.A smoke signal giving off orange colored smoke
C.A whistle signal of one prolonged and three short blasts
D.International Code Signal PAN spoken over the radiotelephone

单项选择题A RADIO SIGNAL FROM A DISTRESSED VESSEL AUTOMATICALLY DIRECTED TO A RCC GIVING POSITION，IDENTIFICATION，COURSE AND SPEED OF THE VESSEL AS WELL AS THE NATURE OF DISTRESS is known as（）.

A.Distress alert
B.Safety alert
C.Emergency alert
D.General alert

单项选择题You receive a call from the MSA OF CHINA addressed to all stations. The call begins with the words Pan-Pan (3 times). Which type of emergency signal would this be?（）.

A.Safety signal
B.Urgency signal
C.Distress signal
D.Red alert signal

单项选择题A continuous sounding of a fog-signal apparatus indicates（）.

A.the vessel is in distress
B.the vessel has completed loading dangerous cargo
C.it is safe to pass
D.the vessel is anchored

单项选择题All of the following are distress signals EXCEPT（）.

A.the continuous sounding of any fog signal apparatus
B.giving five or more short and rapid blasts of the whistle
C.firing a gun at intervals of about a minute
D.a barrel with burning oil in it，on deck