The robber was caught by two men police uniform .
A. in; at the once
B. in; at once
C. on,; at the once
D. on; at once
网友回答
A. in; at the once
(答案→)B. in; at once
C. on,; at the once
D. on; at once
解析：in在里面;on在上面;句意:劫匪立即被两个身穿警服的男人抓住了.介词in可以表示穿某种衣服,短语at once立即,不要冠词,故选B.