单项选择题
A.20~40B.30~50C.40~60D.50~70
A.¢1mm,¢2.5mm,¢3mm B.¢1mm,¢2.1mm,¢3mm C.¢2mm,¢2.4mm,¢3mm D.¢2mm,¢2.6mm,¢3mm
A.铝、镁、碳 B.铝、锰、碳 C.铜、铝、锰 D.铜、铝、镁