单项选择题
A.drill stem guide
B.guide frame
C.drill string frame
D.casing guide
单项选择题 A flooded leg on a liftboat would adversely affect the vessel’s stability underway by().
单项选择题 A fixed carbon dioxide extinguishing system for a machinery space,designed WITHOUT a stop valve in the line leading to the protected space,is actuated by().
单项选择题 A fishing vessel displaying the lights shown is().