Which two statements are true about the function of CAC？（） ["CAC provides guaranteed voice quality on a link.","CAC artificially limits the number of concurrent voice calls.","CAC is used to control the amount of bandwidth that is taken by a call on a link.","CAC prevents oversubscription of WAN resources that is caused by too much voice traffic.","CAC allows an unlimited number of voice calls while severely restricting，if necessary，other forms of traffic.","CAC solves voice congestion problems by using QoS to give priority to UDP traffic."]
自我价值保护
包裹运价率是以（）类包裹运价率为基础，其他各类包裹运价率按该类包裹的运价率加成或减成的比例确定。 ["一","二","三","四"]
中国学者研究认为中国成人的肥胖标准是（） ["体重指数大于等于25为超重，大于等于30为肥胖","体重指数大于等于24为超重，大于等于28为肥胖","体重指数大于等于25为超重，大于等于28为肥胖","体重指数大于等于24为超重，大于等于30为肥胖"]
设某公司在生产中需要一种设备，若自己购买，需支付设备买入价120000元，该设备使用寿命为10年，预计残值率5%；公司若采用租赁方式进行生产，每年将支付20000元的租赁费用，租赁期为10年，假设贴现率10%，所得税率40%。要求：作出购买还是租赁的决策。
适应性控制
