as a matter of interest1 spokenINTERESTED used to say that you are asking a question only because you are interested and not because you need to know （只是）出于好奇〔提问时用〕 Just out of interest, how much did they offer you? 我只是好奇地问一下，他们打算给你多少钱？
→ (just) out of interest/as a matter of interest at interest1(3)
2 British EnglishBrE spokenNEED used when you ask or tell someone something that interests you but is not important 出于兴趣，只是好奇 Just as a matter of interest, which school did you go to? 你上的是哪所学校？我只是随便问问。
→ as a matter of interest at matter1(16)