单项选择题
A.920 B.950 C.1000 D.1100
A.9 B.11 C.14 D.16
A.220 B.209 C.340 D.330
A.上层为固定分路 B.上层为磁场削弱 C.上下两层均为磁场削弱电阻 D.下层为磁场削弱
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