The primary group refers to a social group with close interpersonal relationships and strong emotional colors; the second group refers to a social group that has formed formal relationships through clear rules and regulations in order to achieve actual special goals. Based on the above definitions, Which of the following do not involve primary groups:. ["Wang Liying's birthday today, the company employees bought her a birthday cake.", 'Grandpa Zhang is a hundred years old this year, and set up an organizing committee for his juniors.', "Grandma Li was ill and hospitalized, and the village's neighbors came to the hospital to visit her.", 'Zhao Xiaogang chats with his junior high school classmates on WeChat group every day.']