Ключевые слова: adult, air, background, bad, care, chemical warfare, city, close up, destroy, desulfurization, disease, downtown, environment, epidemic, ethnic, face, factory, female, flu, future, gas, girl, global warming, health, human, infection, influenza, local, mask, medical, outbreak, people, pollution, prevention, problem, protect, protection, protective, quality, river, safety, sick, smog, toxic, urban, virus, water, weather, woman, young,