单项选择题
A.40-45cm B.45-50cm C.50-55cm D.55-60cm
A.-650---850KPa B.-650---850Pa C.-600---850Pa D.-650---800Pa
A.8%—10% B.10%—15% C.12—15 D.15—18%
A.≤0.1% B.≤0.5% C.≤1% D.≤2%
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