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

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

A.a green star signal
B.orange-colored smoke
C.red flares
D.the repeated raising and lowering of outstretched arms