In ship construction，keel scantlings should be the greatest（）.

A.greater at the bow and stern
B.reduced at the bow and stern
C.uniform over the length of the vessel
D.uniform over the length of the vessel，with the exception of the machinery spaces，where it is reduced due to increased stresses

A.Safe working load
B.Ship's working lift
C.Starboard wing lift
D.Stress，weight，load

A.crow bar
B.device to force a water tight door against the frame
C.heavy steel beam
D.wedge