单项选择题
0ne function of a hulwark is to（）.
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
单项选择题 0ne of the principal dangers inherent in liquified petroleum gas is（）.
单项选择题 0pen ullage holes in tanks which are not gas-free must be protected by（）.
单项选择题 0ur starboard derrick boom of hatch No.4 is baddly cracked（）that it has become entirely useless.
