站务中心需要负责以下哪些人员的防汛安全教育工作的具体实施（）
A、中心内部人员
B、车站保安、安检
C、车站保洁
D、设备维保人员
参考答案：A, B, C
一个圆柱体,底面直径和高都是6厘米.它的侧面积是多少?体积是多少?
An analyst does research about characteristics of market structures. Excess capacity in perfect competition is most likely:（）
A. less than that in monopolistic competition.
B. equal to that in monopolistic competition.
C. greater than that in monopolistic competition.
