Yesterday _____ 8-year-old boy fell into the river.____boy was saved by a policeman.

A．an; A

B．an; The

C．a; the

D．a; An

在肾结核早期阶段，下列哪种检查方法最有价值（）

A.化验室检查

B.超声检查

C.CT检查

D.MRI检查

E.尿路造影检查