Only when _________ in the afternoon ________ able to leave.

A．the match was over; they were

B．was the match over; were they

C．was the match over; they were

D．the match was over; were they

关于UPS系统冗余配置，以下说法不正确的是（）。

A.N+1串联冗余系统在切换过程备机电流从零立即上升至负荷最大电流，容易对系统运行可靠性产生较大影响

B.N+X并联冗余系统容易存在单机UPS设备负载电流过小，运行效率低的情况

C.2N或M（N+1）模式为配置N台UPS设备，其总容量为系统的基本容量，再配置1台UPS冗余设备

D.2N或M（N+1）模式主要适用于A级机房，系统可用性较高