A.斷斷續(xù)續(xù)的嗡嗡聲 B.連續(xù)均勻的嗡嗡聲 C.時大時小的嗡嗡聲 D.無規(guī)律的嗡嗡聲
A.2.5% B.3% C.3.5% D.4%
A.鐵芯B.繞組C.上層絕緣油D.下層絕緣油