danger signal是什么意思 danger signal怎么读
danger signal的用法和样例
用作名词 (n.)
- A red lamp is used as a danger signal.
红灯用作危险信号。 - The engine also began its whistle-calls of four parts, with which it signalled danger to important crossings.
机车也开始在过重要的道口时，发出断续四响的汽笛声，作为危险信号。
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