phrase If something is said in passing, it is said while talking about something else and is not the main subject of a conversation: 顺便，附带地 When asked if he had told the police about the incident, Mr Banks said he had mentioned it in passing to a detective.被问及是否已将此告诉了警察时，班克斯先生说他曾向一位侦探顺便提过。 In the article, she refers almost in passing to Chris's literary success. She acknowledged their financial support, but only in passing. He amazed us by remembering all sorts of things we had only mentioned in passing. He noted in passing that the film had grossed over $95 million. See also
passingnoun(GOING PAST)
in passing | American Dictionary
in passing
idiom while talking or thinking about something else: Leo mentioned in passing that you are going on vacation next week.