A.Two masthead lightsB.One masthead light and a sidelig……

单项选择题Two barges are being pushed ahead by a tugboat.Which statement is TRUE concerning lights on the barges（）.

A.Each vessel should show sidelights
B.Each vessel should show at least one white light
C.The barges should be lighted as separate units
D.The barges should be lighted as one vessel

单项选择题The type of fog that occurs on clear nights with very light breezes and forms when the earth cools rapidly by radiation is known as（）.

A.Radiation fog
B.Frontal fog
C.Convection fog
D.Advection fog

单项选择题The two vessels underway may collide with（），if they don’t take immediate measures.

A.One to another
B.One the other
C.Each the other
D.Each other

单项选择题The term restricted visibility，when used in the Rules，refers to（）.

A.Situations when you can see vessels on radar that you cannot see visually
B.Visibility of less than half a mile
C.Any condition where visibility is restricted
D.Visibility where you cannot see shore

单项选择题The term PROLONGED BLAST refers to（）.

A.a blast of from five to seven seconds' duration
B.a blast of from five to six seconds' duration
C.a blast of from four to six seconds' duration
D.a blast of from six to seven seconds' duration