单项选择题
A.help keep the deck dry B.prevent stress concentrations on the stringer plate C.protect against twisting forces exerted on the frame of the vessel D.reinfo ce th eside stringers
0ne of the principal dangers inherent in liquified petr...
单项选择题0ne of the principal dangers inherent in liquified petroleum gas is（）.
A.as it warms up it becomes heavier than air B.the way it reacts with sea water C.the strong odor it produces D.its low temperature causes frostbite or freezing
0pen ullage holes in tanks which are not gas-free must ...
单项选择题0pen ullage holes in tanks which are not gas-free must be protected by（）.
A.PV valves B.warning signs C.flame screens D.stop-check valves
0ur starboard derrick boom of hatch No.4 is baddly crac...
单项选择题0ur starboard derrick boom of hatch No.4 is baddly cracked（）that it has become entirely useless.
A.at its goose neck to such a extent B.at it's goose neck to such an extent C.at it's goose neck for such a extent D.at its goose neck to such an extent
