Obama was elected ____ first black president of the United States four years ago and has been elected _____ president again for the next four years.

A．the; the　　

B．the; X

C．X; the

D．a; a

尿胆原强阳性最有可能的是( )

A．正常人生理变化中增加

B．慢性肾衰竭

C．溶血性黄疸

D．梗阻性黄疸

E．肝细胞性黄疸