Ключевые слова: ad, advertising, announcement, blackboard, board, business, chalkboard, class, classroom, commercial, communication, concept, connection, cooperation, coworker, development, drawing, education, engine, engineering, gear, grungy, idea, industrial, learning, machinery, mechanical, mechanism, noticeboard, office, partnership, production, school, success, teaching, team, teamwork, texture, wall, wheel, wooden, work,