Backchannel
（传递消息的）秘密渠道, 特殊途径
🗣️ 情景例句
Good morning, sir. May I help you?
早安，先生。能为您服务吗？
He is indifferent to any and everything.
他对任何事都漠不关心。
Yes, here you go.
喏，就是这个。