单项选择题
A.7mm B.9mm C.5mm D.10mm
A.15kg;30kg B.30kg;15kg C.20kg;45kg D.45kg;20kg
A.0.5‰ B.1.0‰ C.1.2‰ D.0.8‰
A.5~9mm B.1~5mm C.<1mm D.无正确答案
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