电梯运行速度失控时，（）装置可以使电梯强行制停，不使其坠落。 ["缓冲器","限速器－安全钳","超载保护","补偿装置"]
For a lightweight access point to participate in aggressive load balancing，it must have heard the client for how many seconds？（） ["15","10","1","5"]
系统的安全性
预期收入理论
What is the minimum configuration you must do in order to enable multicast support on the CiscoWireless LAN Controller v5.2?（） ["Enable the IGMP snooping capability and define the IGMP timeout period.","Set the Ethernet multicast mode to Enabled， enable the IGMP snooping capability， and define the IGMP timeout period.","Set the multicast monitor function to Enabled， enable the IGMP snooping capability， and define the mandatory data rate to the minimum value supported.","Set the Ethernet multicast mode to Multicast and define the multicast group address."]
某企业本期有关资料如下：单位直接材料成本10元，单位直接人工成本5元，单位变动性制造费用7元，固定性制造费用总额4000元，单位变动性销售与管理费用4元，固定性销售与管理费用1000元。期初存货量为零，本期生产量1000件，销售量600件，单位售价40元。要求分别采用完全成本法和变动成本法计算下列指标：期间成本；
