AVAST means（）.

单项选择题A SEA ROOM TO BE KEPT FOR SAFETY AROUND A VESSEL，ROCK，PLATFORM，ETC.，OR THE PLACE ASSIGNED TO A VESSEL WHEN ANCHORED OR LYING ALONGSIDE A PIER，ETC means（）.

A.Port
B.Commercial area
C.Berth
D.Roadstead

单项选择题A METHOD OF TOWING VESSELS THROUGH POLAR ICE BY MEANS OF ICEBREAKING TUGS WITH A SPECIAL STERN NOTCH SUITED TO RECEIVE AND HOLD THE BOW OF THE VESSEL TO BE TOWED defines（）.

A.Towing operations
B.Rigid coupled towing
C.Close coupled towing
D.Hard coupled towing

单项选择题A MARK OR POSITION AT WHICH A VESSEL IS REQUIRED TO REPORT TO ESTABLISH ITS POSITION defines（）.

A.VTS point
B.Way point
C.Reference point
D.Establishment point

单项选择题（）will the discharging operations take?

A.How long
B.How length
C.How many times
D.How many shift

单项选择题（）will reduce the visibility.

A.dust
B.sea water
C.land sand
D.wind