单项选择题
A.1 B.2 C.3 D.大于3个
A.HB101000/30/120 B.120HBS10/30/1000 C.120HBS10/1000/30 D.120HBS100/30/10
A.MPa B.无单位 C.kgf/c㎡ D.kgf•m/m㎡