按照维护规程的要求，-48V基础电源的衡重杂音电压小于2mv；供电回路全程压降小于（）V。
参考答案：3
He is a financial manager in Wall Street now, but nobody knows he _____ part-time jobs here and there for survival for eight years.
A．does
B．did
C．had done
D．has done
适合观察细菌动力的细菌接种技术是
A．分区划线接种B．斜面接种C．液体接种D．穿刺接种E．涂布接种
