+24V宽电压范围供电系统，通信设备受电端子上电压允许变动范围为（）V至（）V。
参考答案：19；29
- I hope to see Niagara Falls one day. What about going there?
- Niagara Falls would be beautiful, but there is not much to do there.
A．sometimes
B．in the day
C．a day
D．some day
在Access中，报表设计分页符以______标志显示在报表的左边界上。
