There  are _________of  nurses in our school but only _______of them are boys.

A． hundreds, three hundred.

B．hundred, three hundreds

C． hundreds, three hundreds.

D．hundred, three hundred

急性糜烂性胃炎的确诊有赖于

A．呕血与黑便

B．急诊钡餐检查

C．急诊胃镜

D．病史与体征

E．急诊血管造影