维护系统正常运行的接地方法叫（），如三相四线制380V系统变压器中性点接地。
A、工作接地
B、重复接地
C、保护接零
D、中性点接地
参考答案：B
He was once turned down by a primary school for lack of ________ practical teaching experience. But now he has turned out to be one of ________ best teachers in the city.
A．a; a
B．/; the
C．the; the
D．a; the
一个铁皮箱的体积比它的容积大．______．
