班轮的发船间隔必须具有一定的规则性，如远洋运输常以（）为一个班次。

A.月

B.旬

C.周

D.小时

E.分钟

An analyst does research about characteristics of market structures. Excess capacity in perfect competition is most likely:（）

A. less than that in monopolistic competition.

B. equal to that in monopolistic competition.

C. greater than that in monopolistic competition.