Pollution has reached ______ high levels in some urban areas, which is quite worrying. [ ]

A. disturbingly  

B. slightly            

C. exactly        

D. flexibly

食管腐蚀伤后最常发生食管狭窄的部位是()

A．食管入口

B．左支气管压迹处

C．主动脉弓压迹处

D．食管下段横膈以下

E．贲门处