A jack-up drilling unit elevated on the Outer Continental Shelf must have a fog horn that will sound（）.

单项选择题A jack-up drilling rig being towed must（）.

A.turn off all lights that interfere with the navigation lights
B.turn on all available working lights on deck
C.ring the bell rapidly for five seconds once a minute
D.display two black diamonds in a vertical line during the day

单项选择题A helmsman receives the command “Right 15 degrees rudder.”The helmsman’s IMMEDIATE reply should be（）.

A.Aye Aye Sir
B.Right 15 degrees rudder
C.Rudder is right 15 degrees
D.No reply is necessary，just carry out the order

单项选择题A heavy，thick-walled tube，usually steel，used between the drill pipe and the bit in the drill stem to weight the bit in order to improve its performance is called a（）.

A.heavy-walled drill pipe
B.tool joint
C.down hole tool
D.drill collar

单项选择题A heavy steel curved arch constructed athwartships and above the after deck on a towing vessel is sometimes called a（）.

A.main brace
B.tow span
C.jockey bar
D.None of the above

单项选择题A head-on situation at night is one in which you see dead ahead a vessel showing（）.

A.one sidelight
B.one sidelight and a masthead light
C.one sidelight and two masthead lights
D.both sidelights of a vessel and her masthead light(s)