问题：
单项选择。 — Are you free this afternoon?
— No, I"d like to teach the children the piano (钢琴)
[ ]
A. playing
B. what to play
C. play
D. how to play
单项选择。 — Are you free this afternoon?
— No, I"d like to teach the children the piano (钢琴)
B. what to play
C. play
D. how to play
— No, I"d like to teach the children the piano (钢琴)
[ ]
A. playing B. what to play
C. play
D. how to play
参考答案：