Ключевые слова: bicycle, biofuel, biology, bubble, cable, car, clean, concepts, connection, contemplation, corn, cycling, direction, electric car, electricity, environmental conservation, eye, factory, flower, global, ideas, illustration, industry, inspiration, leaf, light bulb, lighthouse, nature, nautical vessel, people, planet earth, pollution, recycling, renewable energy, sailing, skyscraper, social issues, solar panel, sphere, steam, sun, sunflower, symbol, technology, truck, turbine, vitality, wind, wind turbine,