三相异步电动机的旋转磁场的旋转方向与什么有关？
参考答案：三相异步电动机旋转磁场的转向由供电电源的相序决定。
---How did you do in the test yesterday?
-----Not so well. I ______ much better but I misread the directions for writing.
A．will have done
B．could have done
C．must have done
D．may have done
焊工的劳动保护穿戴有什么要求？
