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