A.630MVA B.630kVA C.630VA
A.斷斷續(xù)續(xù)的嗡嗡聲 B.連續(xù)均勻的嗡嗡聲 C.時(shí)大時(shí)小的嗡嗡聲
A.遠(yuǎn)大于 B.略大于 C.等于