单项选择题
A.500t B.50t C.100t D.60t
A.40mm;180mm B.25mm;160mm C.40mm;160mm D.25mm;180mm
A.180±5 B.185±5 C.200±5 D.195±5
A.0.3% B.0.5% C.0.7% D.0.4%
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