肾结石的特征性形状是
A．长条形
B．同心圆形
C．分层状
D．桑葚状
E．鹿角形
参考答案：E
解析：肾结石的特征性形状是鹿角形。
设A={x|x＜5}，B={x|x≥0}，则A∩B=______．
Sam ____ some knowledge of the computer just by watching others working on it. [ ]
A. brought up
B. looked up
C. picked up
D. set up
