Ключевые слова: adult, background, biology, board, business, casual, chalkboard, chemical, chemist, concept, conference, economics, education, formula, future, graph, group, happy, job, knowledge, lab, laboratory, lifestyle, male, man, math, mature, medical, men, occupation, people, person, portrait, professional, professor, project, research, science, scientific, senior, smart, smile, standing, study, studying, technology, virtual, white, worker, writing,