当PLC电源模块的容量不足以供给设备部分所需时，开关量输入输出将产生不可预知的动作。
参考答案：对
—Not getting that job was a big let-down.
—Don't worry. Something better will ________. [ ]
A. fall behind
B. take on
C. go by
D. come along
以下那一项不属于辅助存储器（）
A.软盘
B.光盘
C.内存
D.硬盘
