He likes _____ with his friends.[ ]
A. skiping
B. swimming
C. skip
答案：B
经电流互感器测量30kW三相异步电动机的电流，应选用（）变流比的电流互感器。
A.30/5
B.50/5
C.75/5
D.200/5
简述阿利氏定律。
