Picture a phone ringing and nobody rushing to it. Something stands between the ring and the conversation: a screen with a name on it, a machine recording a voice, or the phone company itself. Every use of the word is that gap — the call arrives, but a filter decides whether it turns into talking. What changes from one use to the next is only who or what is holding the filter.
可以想成這樣一張圖：電話響了，沒有人衝過去接。在「鈴聲」和「講話」之間，多了一道關卡。那道關卡可能是螢幕上的名字，可能是正在錄音的答錄機，也可能是電信公司的線路。這個詞的每一個用法都是這道關卡——電話有打進來，但要不要變成一場對話，先被篩過一次。三個意思差的只是：篩的人是誰。
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