单项选择题
A.粗沙粒 B.细沙粒 C.石子 D.石英砂粒
A.0.3~0.4MPa B.0.3〜0.5MPa C.0.3~0.6MPa D.0.3~0.7MPa
A.光滑 B.平整 C.粗糙 D.光亮
A.5% B.8% C.10% D.15%
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