While working in the countryside, the students a great deal of knowledge on plant life.
A. looked up
B. picked up
C. put up
D. called up
网友回答
A. looked up
(答案→)B. picked up
C. put up
D. called up
解析：词义辨析。looked up抬头看，查找；picked up 学会；put up挂起，张贴；called up给某人打电话。句意：在农村工作时，学生们选学会了大量关于植物的知识。所以选B。