问题补充:
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
答案:
A. brought up
B. looked up
(答案→)C. picked up
D. set up
解析:考查短语辨析。brought up培养,提出,looked up查字典,picked up捡起,偶然学到,set up 建立,句意:山姆只凭看见别人从事电脑工作他就偶然学会了一些计算机知识。故选C。