human
Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
At an art gallery, there are five paintings displayed in one room: a landscape, a portrait, a still life, an abstract piece, and a cityscape. The curator, Mr. Johnson, rearranges the paintings during his lunch break. He moves the landscape painting to the left wall, the portrait to the right wall, and the still life to the center. Before leaving for lunch, he tells the security guard, Mr. Smith, about the changes. While Mr. Johnson is away, a visitor accidentally knocks over the abstract painting and it falls behind the cityscape, making it hidden from view. When Mr. Johnson returns, what does he think happened to the abstract painting?
Provide a very brief response.

### Response:
gpt
Mr. Johnson would likely be concerned upon noticing that the abstract painting is missing from where he placed it. Considering he informed Mr. Smith of the rearrangement, he might first consider the possibility that it was moved again--either by Mr. Smith or another staff member for some reason or by a visitor. If Mr. Johnson then checks with Mr. Smith or looks around the room and discovers the painting behind the cityscape, he is likely to conclude that it was knocked over accidentally, as he was not informed of any intention to change the arrangement after he left.