国际单位制中电流的法定计量单位是()。
A、伏
B、瓦
C、安
D、赫
参考答案:C
—Who ______ you ______with in the second photos?
—Mr. King. [ ]
A. do; talk
B. are; talking
C. is; talking
D. do; talking
引起安定性不良的原因有哪三个?