龋病调查资料分析统计常用指标是

A．恒牙龋均

B．义齿修复率

C．牙松动率

D．乳恒牙比

E．失牙率

Which of the following statements regarding economic costs is most accurate（）

A. Sunk costs involve setting aside payments to retire long-term debt.

B. In the long run, expected average marginal cost is the most relevant cost to the firm.

C. Fixed costs are not a consideration in the short run operating decision, but must be considered in the long run.