单项选择题
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
A jack-up drilling rig being towed must（）.A.turn off al...
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
A helmsman receives the command “Right 15 degrees rudde...
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
A heavy，thick-walled tube，usually steel，used between th...
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
