当系统发生两相短路时，短路电流中除含有正序分量外，还含有（）分量。
参考答案：负序
When they retire, many people over 60 prefer the houses in the country to spend their remaining years to __________ in a large city.
A．it
B．that
C．those
D．which
较长的零件，若沿长度方向形状一致或按一定规律变化时，可以（）。
A.不绘制
B.断开绘制
C.必须全部绘制
