Qac
abbr. quaternary ammonium compound 季铵化合物（杀菌剂）
🗣️ 情景例句
Please accept my apology for not neeting you for lunch Tuesday.
我很抱歉，星期二没有与你一起共进午餐。
By falling we learn to go safely.
吃一堑，长一智。
But the first people who were like ourselves lived so long ago that even their sagas, if they had any, are forgotten.
但是，和我们相似的原始人生活的年代太久远了，因此，有关他们的传说既使有如今也失传了。