on earth 這個片語很容易被人誤以為是 ”世界上” 的意思 但它其實要用在疑問句, 放在疑問詞後面 意思是 ”到底”, “究竟”, 是一種加強語氣的用法 比如本來是要問: Why did you do that? 就把 on earth 放在 why 後面 變成 Why on earth did you do that? (你到底為什麼要那麼做?) What were you thinking? 就變成 What on earth were you thinking? (你當時到底在想些什麼?) Who would do something like that? 就變成 Who on earth would do something like that? (怎麼會有人做出那樣的事?) 不過, 如果疑問詞是 What color, How far, How much… 等的片語時 就不能在後面接 on earth 了 此時會用 exactly 來表示 ”到底”, “究竟” 而且要放在句尾, 前面打個逗點 像: What color do you want, exactly? How much did you spend, exactly? on earth 的 ”髒話版” 就是 the hell 或 the fuck 像 Who the hell / Who the fuck are you? 就是 ”你他媽的是誰呀?” 這種意思 Where the hell / Where the fuck have you been? 就是 ”你他媽的死到哪兒去了?”