低压系统(指1kV以下交流系统电源系统)接地型式有()三种接地制式。
A．TN
B．TT
C．IT
D．TN-C-S
参考答案：A,B,C
He was very ____ to find his suggestion ____.
A．disappointed; to be turned down
B．disappointing; turned down
C．disappointed; turned down
D．disappointing; turning down
白芍的产地加工应为( )
A．晒干
B．去皮晒干
C．去皮，煮透心后晒干
D．去皮阴干
E．开水浸泡后晒干
