单项选择题
A.20g B.40g C.50g D.60g
A.32.5 B.42.5 C.52.5 D.52.5R
A.±1s B.±2s C.±1.5s D.±2.5s
A.≤4.0% B.≤5.0% C.≤6.0% D.以上都不是
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