单项选择题
A.38kg/m B.43kg/m C.50kg/m D.60kg/m
A.100mm B.120mm C.150mm D.180mm
A.450mm B.500mm C.550mm D.600mm
A.0.088m/m B.0.10m/m C.0.22m/m D.0.27m/m
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