The next morning, 38 however , their happiness disappeared. Someone had left a 39 note under their door during the night. One of their neighbors had written to complain(抱怨) about the sound of the piano. Dario’s mother asked the building superintendent(管理员) if he knew anything about it. But he said that they were all 40 nice people and he couldn’t imagine any of them had done that. Later that morning, Dario suggested that they write a letter to their 41 neighbors and apologize for their playing.