分析和说明变压器一次侧接通电源后，二次侧没有电压的原因。
参考答案：
一次绕组开咱或引出线脱焊；二次绕组开咱或引出线脱焊；电源插头或馈线开路。
It was because of his absence _____ the meeting had to be put off. [ ]
A. so
B. so that
C. why
D. that
藜芦与细辛的配伍属
A．相使
B．相畏
C．相恶
D．相反
