Op. cit.
abbr. 前面引用的书(in the work already quoted)
🗣️ 情景例句
Interesting. What do you photograph?
很有意思。你拍些什么样的照片呢？
Wit once bought is worth twice taught.
亲身一次的经验，抵得上老师两次的教导。
Oh, sorry.
哦，对不起。