已知某企业生产电水壶，产品单价为500元，变动成本率为40%，固定成本总额为90000元，则企业的保本量为（）件。 ["200","300","500","600"]
人本治疗模式的治疗特点？
Acme Nutrition manufactures a wide variety of vitamin supplements. It has a single manufacturing facility with 3 regional warehouses and 16 district sales offices. Currently the manufacturing facility requires 210 IP addresses; each warehouse requires 51 IP addresses; each district sales office requires 11 IP addresses; and the IP WAN requires 38 IP addresses. if Acme Nutrition plans for 20 percent growth in facilities, how many Class C subnets will the district sales offices require?（） [" 19 (3 from the warehouse range and 16 from a separate Class C address)"," 19 (3 from the warehouse block, 15 from a separate Class C block and 1 from the IP WAN block)"," 20 (4 from the warehouse range,15 from a separate Class C block and 1 from the IP WAN block)"," 16 (3 from the warehouse range and 13 from a separate Class C address)"]
常年保障应急供电业务（）。 ["需制定详细的应急电源保障预案","断电后需在约定时间内到达保障现场","用户负荷增加，原有应急预案无需变更","常年备勤，提供7×24小时业务受理"]
简述母岩风化的产物及其所形成的岩石。
简述课堂学习管理的基本原则。
