单项选择题
A.2.75或2.5B.3.05或3.2C.3.3或3.5D.3.6或者3.8
A.抗疲劳性越好 B.抗强度性越好 C.抗韧性越好 D.抗硬度性越好
A.0.5mg B.0.7mg C.0.8mg D.0.9mg
A.0.15% B.0.17% C.0.19% D.0.20%
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