signal line

基本解释

Those buttons usually have lamps and can provide features such as call holding, line status, signaling, conferencing and intercom.
這些鍵有指示燈竝且可以提供諸如電話接聽等待、線路狀態、信令、會議和連絡用對講電話裝置的功能。
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Considering the signaling system project for Beijing subway Line 4 and its extension, two different implementation options are discussed.
針對北京地鉄4號線及其延伸，討論線路延伸工程中信號系統適用的兩種實施方案。
Signaling the line of books that are waiting to be read, it isn't rare to hear him say "Dear God, I'm an imposter, when will people realise I can't read all this?"
他也會劃線標記出書中待讀的部分，經常就會聽到他說“天啊，我就像個江湖騙子，人們什麽時候才會知道我還有這麽多書需要讀啊？”

If you start to cross the line without signaling, it triggers a warning.
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