Ключевые слова: accident, alert, attention, background, biogas, burn, caution, cell, chemical, compressed, concept, danger, dangerous, door, emergency, enter, explosion, explosive, extreme, factory, fire, flame, flammable, forbidden, fuel, gas, hazard, hazardous, heat, industrial, industry, no, not, oxygen, phone, possibility, protection, protective, red, risk, safety, security, sign, smoking, substance, symbol, toxic, unsafe, warning, zone,