电气设备的高、低压是如何划分的？
参考答案：
电气设备的高、低压的划分：
高压：设备对地电压在250V以上者；
低压：设备对地电压在250V及以下者。
在下列字符中，其ASCⅡ码值最小的一个是______。
A) 空格字符 B) 9C) A D) a
Never ______ so excited because it is the first time that I ______ such a fantastic experience.
A．I have been; had
B．have I been; have had
C．have I been; had had
D．I have been; have
