A.350mm B.400mm C.450mm D.500mm
A.0.25 B.1 C.0.75 D.0.5
A.氣孔 B.未焊透 C.夾渣 D.裂紋
A.非自航船 B.躉船 C.非自航船和躉船 D.小型船舶
A.10s B.15s C.20s D.25s