依据免维护蓄电池的工作原理，太阳能充电控制器对免维护蓄电池的最高充电电压进行控制，电压为12V的最高充电电压为14.3V。
参考答案：对
At whatthe child said, the people present were puzzling.
A B C D
— May I _____ Helen?
— This is Helen speaking. [ ]
A. speaking
B. speak
C. speak to
