单项选择题
A.3d或4dB.1d或2dC.4d或5dD.2d或3d
A.1~2minB.2~3minC.3~4minD.5~10min
A.气孔、未熔合、条状夹渣B.未熔合、气孔、裂纹C.裂纹、气孔、条状夹渣D.裂纹、未熔合、条状夹渣