Ключевые слова: 2018, abstract, ahead, arrow, autumn, back, backward, change, circle, clock, concept, day, decision, europe, fall, go, hours, law, leaves, maple, minutes, move, numbers, october, one, problem, question, regula, rotate, round, rule, step, summer, summetime, symbol, time, transfer, utc, walk, wall, watch, white, winter, wintertime, wood, work, world, yellow, zone,