A.at
B.on
C.in
D.above

A.Static electricity
B.An open and running motor
C.Loose wiring
D.All of the above

A.at
B.in
C.on
D.over

A.Lacings
B.Lays
C.Strands
D.Twines

A.Feeling the surface of the line for broken fibers
B.Measuring the reduction in circumference of the line
C.Observing for the appearance of mildew on the outer surface
D.Opening the strands and examining the inner fibers

A.of
B.to
C.on
D.with

A.I am altering my course to starboard
B.I am altering my course to port
C.I am operating astern propulsion
D.I am operating ahead propulsion

A.stop down
B.speed down
C.slow down
D.down slow

A.Bow line
B.Breast line
C.Spring line
D.Stern line

A.existing visibility conditions，limited only by the curvature of the Earth
B.perfect visibility conditions，limited only by the curvature of the Earth
C.existing visibility conditions，limited only by the intensity of the light
D.perfect visibility conditions，limited only by interference from background lighting

A.Hard rubber
B.Canvas
C.Leather
D.Sponge rubber