变压器的单相接地保护装置可启动（）继电器。
A.电流
B.信号
C.中间
D.零序
参考答案：D
轴型皮瓣可分哪几种类型?
Your school things should _____.
A．be looked after well
B．be looked well after
C．be taken good care
D．be taken care of well
