目前110kV、220kV采用最多的接地保护方式是由（）和（）组成三段或四段阶梯式保护。
参考答案：零序方向速断；零序方向过流
I hope that my father will quit smoking because I want him to live my grandpa does.
A．as a long and healthy life as
B．as long and healthy a life as
C．such long and healthy a life as
D．so long and healthy a life as
2～3岁呼吸频率为：
A．40～45次/分B．20～25次/分C．18～20次/分D．25～30次/分E．30～40次/分
