【单选题】ZPW-2000A系统中,由于60kg重1435mm轨距的钢轨电感为1.3mH/m,同时每米约有数pF电容。对于1700Hz、2300Hz的移频信号,钢轨呈现较高的感抗值,该值大大高于道砟电阻时,对轨道电路移频信号的传输产生较大的影响。为此,需在两钢轨间等距离加 ( ) ,以减弱电感的影响。
【简答题】Holidays are often associated with no work and all play. People seek to enjoy their holidays in different ways. Vacation packages (一揽子交易) have been in existence for a long time. ---小题1:--- So now peop...
【单选题】下列不属于工程造价中计算分部分项工程人工、材料、机械台班消耗量及费用依据的是( )。
【单选题】听力原文:Stem cells are undeveloped human cells that can grow into many or all of the different specialized cells in the human body. Although stem cells have been harvested from adults, the most versatile...
A.
It discusses fertility clinics.
B.
It defines stem cells.
C.
It mentions artificial fertilization.
D.
It identifies the origins of stem cells.
【简答题】直接费用指在施工中直接用于工程实体上的人工、材料、设备和施工机械使用费用的总和。下列不属于直接费用的是()。 A设备费 B临时设施费 C材料费用 D施工机械费
【简答题】对于1700HZ~2300HZ移频信号,钢轨相当于一个感性负载,为了保证轨道电路的传输长度,需在线路上加装 、且该设备在区间通常按照 设置。