哪些部位在CT扫描时需口服对比剂()
A.胸部
B.四肢关节
C.腹部
D.颅脑
E.盆腔
参考答案:C, E
We offered these students a summer course, aimed_____ improving their spoken English. [ ]
A. to
B. in
C. at
D. for
表面粗糙度愈大,则表面光洁度愈低。