This is clipart converted and broken apart that has been released into the public domain because the document says so, and its from NASA, a USA government agency. The publication is called "The Brain in Space:" http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/The.Brain.in.Space.html 美國國家航空航天局 空間 科學 58294main_The.Brain.in.Space-頁面-98-以斯帖-樓梯
Sign to mark your stairwell with silhouette of a spiral staircase in art nouveau style, part of a series. 樓梯 樓梯間 樓梯 樓梯間門標誌
fall cartoon down piano stairs falling addon falls staircase downstairs Addon Piano Falls Down Stairs clip art 載入項 地板 秋天 載入項鋼琴樓梯落下來的剪貼畫