Hardly _______ to speak when the audience interrupted him.

A．he began

B．he had begun

C．had he begun

D．did he begin

SS4型电力机车牵引控制柜中电子插件分板测试，±15v板测试，插入插件，合逆变电源开关，插件面板两个uD灯亮，调w1使1号脚输出（）。

A、（+5±0．1）V

B、（+104-0．1）V

C、（+15±0．1）V

D、（+20+0．1）V