A.250 B.300 C.350 D.450
A.避雷針長(zhǎng)度 B.引下線根數(shù) C.引下線材質(zhì)規(guī)格 D.接地極材質(zhì)規(guī)格
A.0.5 B.0.7 C.1.0 D.1.5