A hand held instrument used to measure distances between objects and the ship is a（）.

单项选择题A green buoy has a yellow triangle on it. This is a(n)（）.

A.information or regulatory buoy that has lateral significance
B.buoy that is off-station and is marked to warn mariners of its wrong position
C.dual purpose marking used where the ICW and other waterways coincide
D.buoy that was set in error and will be replaced with a red nun buoy

单项选择题A frame with two，or sometimes four，arms through which are threaded the guidelines and which is used to keep the drill stem and bit in line with the center opening in the temporary guide base is the（）.

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（）.

A.increasing the righting moment
B.decreasing the vessel's displacement
C.increasing the reserve buoyancy
D.shifting the CG (center of gravity) off center

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（）.

A.one control
B.two controls
C.three controls
D.none of the above

单项选择题A fishing vessel displaying the lights shown is（）.

A.anchored
B.underway but not fishing
C.tending a small fishing boat
D.fishing by trawling