银联标识从左至右一次是()三种颜色。
A.红、蓝、绿
B.红、绿、蓝
C.蓝、绿、红
D.绿、红、蓝
参考答案:A
SQL语言中,能正确实现级联删除的命令是
A.ON DELETE CASCADES
B.ON DELETE RESTRICTED
C.ON DELETE NULLIFIES
D.ON DELETE DEFAULT
PLC的输出方式为晶体管型时,它适用于直流负载。