Ключевые слова: backgrounds, blue, color, concepts, counterweight, energy, equipment, exploration, fossil, fuel, gas, gasoline, geology, industrial, industry, lever, machine, natural, nobody, oil, oilwell, old, outdoors, pipeline, pollution, power, prairie, prosperity, pulley, pump, reservoir, resource, rig, rusty, scenics, silhouette, sky, steel, sunlight, tank, wealth,