翻譯: 當你需要複印時,你會做什麼。
at/in which = where
What do you do when you need to make photocopies.當您需要復印時,您會怎麼做。photocopies 影印、複印;photocopy的名詞複數
23. What do you do _____ you need to mak..-阿摩線上測驗