Credit Reference: http://blog.tutorming.com/mandarin-chinese-learning-tips/why-do-chinese-people-ask-have-you-eaten
"吃了吗 (Chī le ma)?" (also "吃饭了吗 (chī fàn le ma)"
Many Westerners who study Chinese recognize "吃了吗?" as the textbook standard in Chinese greetings.
"吃了吗?" is still commonly used among the older generation in Northern China, especially in Beijing. Please note that you need to have a certain degree of familiarity to use "吃了吗?", as it is most often used between old friends and neighbors.
What literary device would we associate with the aforementioned Chinese old fashioned way of greeting?