Ключевые слова: abandoned, abstract, background, black, blue, building, channel, cold, complex, concrete, dark, deep, distribution, floodgates, flow, fresh, hole, icon, illustration, land, mechanisms, metal, mountain, network, nose, old, open, plants, precision, primary, regulatory, river, round, sea, secondary, sky, source, sun, system, tertiary, tunnel, two, warm, water, wave,