A.220 B.209 C.340 D.330
A.上層為固定分路 B.上層為磁場(chǎng)削弱 C.上下兩層均為磁場(chǎng)削弱電阻 D.下層為磁場(chǎng)削弱
A.750 B.800 C.830 D.810