Backchannel
（传递消息的）秘密渠道, 特殊途径
🗣️ 情景例句
there isn't any work for a retired person my age.
没有我这种年纪的退休老人的工作。
Why are you sitting over there?
你为什么坐在那里？
Knowledge began to increase as soon as the thoughts of one individual could be communicated to another by means of speech.
人一旦能用语言同别人交流思想，知识的积累便开始了。