A.slipwayB.graving dockC.ground warpD.caisson dockA lar……

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

A.a 2-second blast every 20 seconds
B.a 4-second blast every 20 seconds
C.an 8-second blast every 30 seconds
D.a 10-second blast every 30 seconds

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