电流流过负载时,负载两端就有电压,把这个电压叫做()。
A、电压值
B、电压降
C、电位差
D、电势值
参考答案:B
— Listen, there is some strange noise.This machine must be ________.
— I think so.You must have it checked.[ ]
A. out of order
B. out of date
C. out of sight
D. out of control
历史学与其他社会科学的关系。