By playing with the native boys and girls one can a lot of their language.A. pick upB. se

问题补充：

By playing with the native boys and girls，one can a lot of their language.

A. pick up

B. set up

C. build up

D. put up

答案：

A. pick up

B. set up

C. build up

D. put up

解析：A

解析考查动词短语辨析。句意为：与本土的孩子们玩可以顺便学会许多他们的语言。pick up(偶然)获得，听到，学会，符合句意。