He wants to be a police officer,____ it's an exciting job. [ ]

A. and  

B. so  

C. because  

D. why

男，35岁，因服吲哚美辛数片后觉胃痛，今晨呕咖啡样胃内容物400ml来诊。既往无胃病史。首选的检查是

A．血清胃泌素测定

B．B型超声检查

C．X线胃肠钡餐

D．急诊胃镜检查

E．胃液分析