输尿管结石
A． * * 外口狭窄B． * * 膜部损伤C． * * 假道形成D． * * 内口狭窄E． * * 球部损伤
参考答案：A
Two people were killed in the serious car _______ the other day.
A．strike
B．break
C．crash
D．incident
用分段采样法采集的样品，需要（）分析。
A.混合后
B.间隔
C.随机
D.逐个
