Ключевые слова: abstract, advertisement, back, backdrop, background, black, blackboard, blank, board, chalk, chalkboard, class, close, closeup, communication, concept, copy, dark, design, detail, distressed, education, element, empty, floor, gray, green, grey, grunge, grungy, learning, light, material, message, natural, nature, nobody, old, pattern, school, slate, space, stone, surface, text, texture, textured, vintage, wall, wallpaper,