Ключевые слова: adult, african, american, audience, back, bearded, business, businessman, casual, cell, cellphone, chairs, colleagues, conference, education, event, explaining, group, hall, holding, indoor, lecture, listening, male, man, many, meeting, mobile, multimedia, office, participants, people, person, phone, presentation, professor, projector, public, screen, seminar, sitting, smart, smartphone, speaker, speaking, technology, training, video, view, watching,