单项选择题 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（）.

单项选择题 A self-contained breathing apparatus is used to（）.

单项选择题 A damaged T-Boat that is unable to meet the requirementsof its Certificate of Inspection but is able to travel to a shipyard under its own power should（）.