Without proper lessons you could a lot of bad habits when playing the piano.A. give upB.

问题补充：

Without proper lessons, you could a lot of bad habits when playing the piano.

A. give up

B. catch up

C. pick up

D. keep up

答案：

A. give up

B. catch up

(答案→)C. pick up

D. keep up

解析：考查动词短语辨析。A放弃；B追上，赶上；C捡起；用车接；无意中学会；接受信号；康复。恢复；染上…；D保持，跟上；句意：没有合适的教学，当你在弹钢琴的时候，你可能会染上很多的不好的习惯。根据句意说明C项正确。