单项选择题
A.R≤250/I B.R≤2000/I C.R≤12 D.R≤10
A.0.8,1.2 B.0.8,1.8 C.0.6,1.2 D.0.6,1.8
A.6 B.8 C.10 D.15
A.5 B.10 C.12 D.15
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