单项选择题
A.HM、HW和HN B.HW、HN和HM C.HW、HM和HN D.HN、HM和HW
A.8mm,12mm B.12mm,8mm C.8mm,8mm D.12mm,12mm
A.I500a B.I50a C.I50b D.I50c2-73.热轧H型钢