A.對(duì)地電壓 B.沖擊電壓 C.對(duì)稱(chēng)電壓 D.標(biāo)稱(chēng)電壓
A.相當(dāng)于零 B.為零 C.很小 D.無(wú)窮大
A.±2mm B.±2.5mm C.±1.5~2mm D.±2~2.5mm