[名词解释] 酸性降水

食管静脉曲张的影像学检查方法中最常应用的简便有效的方法是 ["A．食管钡餐检查","B．食管CT检查","C．食管MRI检查","D．血管造影检查","E．超声检查"] 干沉降 下列疾病中，没有龛影表现的是 ["A．食管憩室","B．胃溃疡","C．胃癌","D．食管癌","E．肠结核"] 硫酸烟雾型污染 右侧膈下游离气主要须相鉴别的症状是 ["A．胃泡","B．间位结肠","C．先天性巨结肠","D．气胸","E．气肿性胆囊炎"] 酸性降水