车站报站器不可能接收()
A.控制中心控制指令
B.车站值班员人工控制信号
C.来自轨道电路控制信号
D.来自ATS控制信号
参考答案:A
两导体电阻之比为3:1,则串联时两导体两端电压之比为______,相等时间内通过两导体电流所做功之比为______;若两导体并联,则两导体中的电流之比为______,相等时间内通过两导体电流所做功之比为______.
“I’m more nervous right now than when I _______,”Jane said ,as she saw a group of reporters waiting anxiously at the exit of the gymnasium.
A.had competed
B.competes
C.was competing
D.have competed