单项选择题
Fog forms when the air（）.
A.is 50% water saturated
B.is 90% water saturated
C.temperature is greater than the dew point temperature
D.temperature is equal to，or below the dew point temperature
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相关考题
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Five or more short blasts on a vessel’s whistle indicates that she is（）.
A.in doubt that another vessel is taking sufficient action to avoid a collision
B.altering course to starboard
C.altering course to port
D.the stand-on vessel and will maintain course and speed -
单项选择题
After a vessel transmits the original distress message，what signal should be sent to allow ships to take RDF bearings?（）
A.SOS three times
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C.E for one minute，followed by T for one minute
D.Two tones，10-15 seconds each -
单项选择题
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A.Pan-Pan (3 times)
B.Securite Securite Securite
C.TTT TTT TTT
D.No special prefix
