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單項選擇題

A special device that，when fitted into the rotary table，transmits torque to the kelly and simultaneously permits vertical movement of the kelly to make the hole is called a（）.

A.master bushing
B.kelly slips
C.kelly bushing
D.rotary bushing

單項選擇題

A self-contained breathing apparatus is used to（）.

A.make underwater repairs to barges
B.determine if the air in a tank is safe for men
C.enter areas that may contain dangerous fumes or lack oxygen
D.resuscitate an unconscious person

After riveting is completed，the joints on the shell of a vessel are generally made watertight by（）.

你可能感興趣的試題

A special device that，when fitted into the rotary table，transmits torque to the kelly and simultaneously permits vertical movement of the kelly to make the hole is called a（）.

A self-contained breathing apparatus is used to（）.

After riveting is completed，the joints on the shell of a vessel are generally made watertight by（）.

A special device that，when fitted into the rotary table，transmits torque to the kelly and simultaneously permits vertical movement of the kelly to make the hole is called a（）.