Ключевые слова: art, backgrounds, black, business, car, carriage, design, drop, element, energy, environment, equipment, fossil, fuel, gas, gasoline, illustrations, industrial, industry, isolated, machine, mode, objects, oil, painting, petroleum, pipe, pipeline, power, pump, reservoir, resource, silhouette, symbol, technique, technology, tower, transport, transportation, valve, vehicle, wealth, white, working,