引起输尿管梗阻最常见的病因为（）
A.泌尿系感染
B.输尿管肿瘤
C.肾结核
D.肾结石
E.先天性狭窄
参考答案：D
Attempts have been made for nearly three decades to increase the amount of precipitation from clouds by seeding them with salt or silver iodide.
A．Devices
B．Hypotheses
C．Efforts
D．Suggestions
适宜胸膜内胸廓成形术的脓胸是（）
A.病程久，肺有纤维变性的脓胸
B.急性包裹性脓胸
C.小儿脓胸
D.病程短，肺组织无病变的脓胸
E.以上都不是
