A.大于零 B.等于零 C.小于零 D.無(wú)法判斷
A.零 B.無(wú)窮大 C.負(fù)載電壓 D.電源電動(dòng)勢(shì)
A.將機(jī)車(chē)上AC220V轉(zhuǎn)換為DC50V B.將機(jī)車(chē)上DC220V轉(zhuǎn)換為DC50V C.將機(jī)車(chē)上AC110V轉(zhuǎn)換為DC50V D.將機(jī)車(chē)上DC110V轉(zhuǎn)換為DC50V