单项选择题
In plugging submerged holes on a vessel，rags，wedges，and other materials should be used in conjunction with plugs to（）.
A.reduce the water pressure on the hull B.reduce the water leaking around the plugs C.prevent progressive flooding D.reduce the possibility of stress fractures
单项选择题 By definition，a spar deck is the（）.
单项选择题 Bulkheads which form part of the tanks on a vessel are stiffened to withstand（）.
单项选择题 Between the side frames on a vessel，support for the deck beams is provided by（）.
