C66 Raising Children to Protect Them from Old Age

On the way back, I asked Teacher Xia, "Teacher Xia, how did you know that the student today was a fourth-year student? You know him? "

Teacher Xia replied with a smile, "How would I know him? I don't teach first-year students. It's just that I met him in the corridor after class. He walked with me through the same corridor. He thought it was either one three or one four