单项选择题
A.1孔 B.2孔 C.3孔 D.4孔
A.4 B.3 C.9 D.12
A.士1.0% B.士1.5% C.1.0% D.1.5% E.2.0%
A.1GPa B.0.1MPa C.0.1GPa D.5MPa E.1MPa
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