单项选择题

In order for combustion to occur inside a piping system such as a vapor collection header in a marine emmission control system , there must be（）.

A.fuel
B.oxygen
C.ignition
D.All of the above

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单项选择题

In order to correctly open a new coil of manila line,you should（）.

A.pull the tagged end from the top of the coil
B.pull the tagged end through the eye of the coil
C.secure the outside end unroll the coil
D.unreel the coil from a spool

单项选择题

In order to detect rot in manila lines,you should（）.

A.feel the surface of the line for broken fibers
B.measure the reduction in circumference of the line
C.observe any mildew on the outer surface
D.open the strands and examine the inner fibers