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

问题补充：

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

A. keep up

B. pick up

C. make up

D. catch up

答案：

A. keep up

(答案→)B. pick up

C. make up

D. catch up

解析：本题考查动词短语辨义。keepup继续，保持；pickup学到，养成；drawup靠近，拟订，制定；catchup赶上。根据句意“你如果学习方法不适当，弹钢琴时就会养成很多坏习惯。”可知，该题的正确答案为B项。