单项选择题
钢轨顶面上有长度大于(),且深度大于()的掉块,判为钢轨折断。
A.30mm,5mm
B.50mm,2mm
C.50mm,5mm
D.25mm,5mm
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单项选择题
A.30mm,5mm
B.50mm,2mm
C.50mm,5mm
D.25mm,5mm
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