柯林斯詞典sit in on (sitting,sat,sits) 1. PHRASAL VERB If you sit in on a lesson, meeting, or discussion, you are present while it is taking place but do not take part in it. 列席; 旁聽 Will they permit you to sit in on a few classes as an observer? 他們會允許你旁聽幾節(jié)課嗎？ 返回 sit in on