单项选择题
A.0.6~0.8m B.0.8~1.2m C.1.2~1.5m D.1.5~1.8m
A.100~200mm B.200~300mm C.300~400mm D.400~500mm
A.2~4m B.4~6m C.6~8m D.8~10m
A.0.2% B.0.4% C.0.1% D.0.3%
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