Sam some knowledge of the puter just by watching others working on it．
A. brought up
B. looked up
C. picked up
D. set up
网友回答
A. brought up
B. looked up
(答案→)C. picked up
D. set up
解析：考查固定短语。brought up抚养长大；．looked up查找，检查；picked up拾起，捡起，偶然学会；set up设立，建立。Sam通过看别人操作学会了一些电脑知识。所以选C。