单项选择题
A.浇筑孔B.检查孔C.观察孔D.清理孔
A.≥50%B.≥70%C.≥75%D.≥100%
A.0.1%~0.2%B.0.1%~0.3%C.0.1%~0.4%D.0.1%~0.5%
A.50%B.75%C.85%D.100%
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