Have you ever wondered ______ there are so many natural disasters across the world in 2010?

A．which it is that

B．what is it that

C．how it is that

D．why it is that

患者男，53岁，因“进行性吞咽困难6个月”来诊。无其他不适症状。上消化道造影：胸中段食管充盈缺损，黏膜紊乱、中断，局部有软组织影。查体：双侧锁骨上区未触及肿大淋巴结，心、肺、腹无特殊发现。

为明确诊断及确定病期应进行的检查项目有（）

A.食管镜活检

B.食管超声内镜

C.胸部CT

D.腹部B型超声

E.气管镜

F.全身骨显像