男性患者，36岁。间断黏液血便8年，加重2个月。每天大便次数为5～6次，为明显血便，粪质少。辅助检查：Hb126g/L；ESR20mm/h；肠镜示直肠至肝曲黏膜明显充血、水肿，散在针尖样溃疡，黏膜质脆，触之易出血。大便潜血（++）。

该患者突然出现发热、腹痛，排便、排气停止。查体：腹膨隆，全腹压痛、反跳痛及肌紧张，肠鸣音消失。患者出现该并发症的诱因是（）。

A.钡剂灌肠

B.低钾血症

C.抗胆碱能药物的应用

D.全腹CT检查

E.肠镜检查

F.阿片类制剂的应用

Which of the following statements is most accurate regarding a firm’s cost of preferred shares A firm’s cost of preferred stock is:（）

A. the market price of the preferred shares as a percentage of its issuance price.

B. the dividend yield on the firm’s newly-issued preferred stock.

C. approximately equal to the market price of the firm’s debt as a percentage of the market price of its common shares.