Ключевые слова: backgrounds, building, business, chimney, coal, color, dioxide, dock, energy, factory, forest, fossil, gas, generator, grass, green, heavy, history, horizon, horizontal, industry, kauai, leaf, meadow, mill, mirror, moored, mountain, nature, no, over, panoramic, pattern, people, pollution, power, river, ship, sky, station, steel, substance, summer, sun, tower, transportation, travel, tree, unhealty, water,