已知在某位计数制下2*3=10，根据这一规则3*5应等于( )。
A．15 B．17 C．21 D．23
参考答案：B
Assume that a firm has an expected dividend payout ratio of 20%, a required rate of return of 9% , and an expected dividend growth of 5%. What is the firm's estimated price-to-earnings (P/E) ratio（）
A. 5.00.
B. 10.00.
C. 20.00.
板式塔的优点有（）。
A.结构简单
B.制造维修方便
C.成本低
D.流体阻力小、生产能力和塔板效率高
