Ключевые слова: alternative, bulb, cloud, colorful, concept, conservation, consumption, desert, earth, ecological, electricity, energy, environment, environmental, future, glass, global, green, hope, innovation, invention, lamp, light, lightbulb, mountain, natural, nature, object, outdoor, planet, plant, power, process, protect, recycle, renewable, resource, reusable, sky, solution, star, sunlight, sunset, sustainable, symbol, technological, technology, tree, warming, water,