Ключевые слова: anxiety, background, business, choose, concept, customer, emoticon, emotion, excel, excellence, experience, face, feedback, good, happiness, happy, health, hope, ladder, laugh, life, loading, marketing, mental, mind, mood, negative, opinion, poll, positive, preform, psychology, quality, question, rank, ranking, rating, research, review, sad, satisfaction, service, smile, stress, survey, symbol, test, thought, unhappy, user,