Ключевые слова: alertness, attention, background, bacterium, bike, biology, canada, caution, chaos, closing, control, coronavirus, covid19, crisis, danger, entry, epidemic, forbidden, government, illness, kids, no people, outdoor, pandemic, person, plastic, playground, prevention, protection, quarantine, road, safety, security, sign, site, solitude, square, stop, striped, symbol, tape, traffic, vertical, virus, warning, way, zone,