What did he do in the middle of the night?Well.I'm not sure.but he was often
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What did he do in the middle of the night？Well，I'm not sure，but he was often heard ________．
A.playing the piano
B.to play piano
C.play the piano
D.to be playing piano
试题答案
A
用现在分词作补足语；piano前应用the。