Which of the following is a discrete random variable（）

A. The amount of time between two successive stock trades.

B. The realized return on a corporate bond.

C. The number of advancing stocks in the DJIA in a day.

腹部闭合性损伤后，腹痛、腹部局限压痛，轻度肌紧张，一般情况可。处理原则是()

A．禁食

B．腹平片检查

C．立即剖腹探查

D．必要时可行腹腔穿刺

E．严密观察腹部体征及血尿便常规变化