用户工作区的终端设备可以是()。
A.电话机
B.PC机
C.传感器
D.检测仪
E.交换机
参考答案：A, B, C, D
解析：交换机属于设备间子系统
—I'm sorry, I broke your pen. Let me buy you a new one.
—______ I have another one. [ ]
A. You're always so careless.
B. Thank you.
C. Never mind.
D. That's right.
机械密封的动环、静环、密封圈、弹性元件的工作状态如何？
