_____ does it take you to get there? [ ]
A. How far
B. How long
C. How often
D. How
答案:B
哪些情况下应立即停止变压器运行?
交流电焊机在使用中噪音过大,不可能是()
A.电焊机过载
B.电抗器短路
C.部分线圈断路