My brother is studying in ______ university in America; he wants to be ______ astronaut in the future.

A．a; a

B．a; an

C．an; a

D．an; an

一马，无尿，腹腔穿刺有大量尿液，该马所患病为（）。

A.膀胱炎

B.膀胱破裂

C.肾炎

D. * * 狭窄

E.肾结石