A.磁芯B.金屬芯C.電磁芯D.絕緣芯
A.電源的儲(chǔ)能很大B.電路的儲(chǔ)能很小C.電路的儲(chǔ)能很大D.電源的儲(chǔ)能很小
A.電勢(shì)差B.電勢(shì)高C.電勢(shì)低D.電勢(shì)穩(wěn)定