單項選擇題

A V-shaped ripple with the point of the V pointing upstream in a river may indicate a（）.

A.submerged rock, not dangerous to navigation
B.sunken wreck, not dangerous to navigation
C.towed-under buoy
D.All of the above

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單項選擇題

A wet cargo refers to（）.

A.a cargo that will be damaged if it gets wet
B.bulk liquids
C.cargoes that will cause condensation
D.liquids in containers

單項選擇題

A wildcat ia a（）.

A.deeply-grooved drum on the windlass with sprockets with engage the links of the anchor chain
B.winch that running out of control due to a failure of the overspeed trips
C.line that has jumped off the gypsyhead while under strain
D.nylon line that parts under strain and whips back in a manner