—_______ didn't she come to school yesterday?

—Because she was ill.  [ ]

A. When    

B. Why      

C. Where    

D. How

患者女性，55岁，近3个月来出现胸骨后疼痛，伴有反酸、胃灼热、嗳气，症状常于进食后或平卧时加重，1周来疼痛症状加重。

为进一步确诊应首选哪项检查

A．24h食管pH监测

B．胃镜+组织活检

C．食管吞钡X线检查

D．超声内镜

E．食管滴酸试验