The fighting starts when a signal such as an air horn or whistle blows, and can last anywhere from a few minutes to a few hours.

当用号角或口哨发出信号时，大战就可以开始了，在任何位置都行，能持续几分钟到几个小时。

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By single chip computer control of counter automatically generate tong 1 second stop 4 seconds of signal, make no. 5 relay output drive electric horn turns electrify.

由单片计算机控制的计数器自动产生通1秒停4秒的信号，使5路继电器输出带动电喇叭轮流通电。

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We use this air horn to give a signal in the event of emergency.

应急情况下，用这个气喇叭发信号。

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The switchman examined the switch again, checking that the express had done no damage, then went into his cabin, pulled the door to, and played a few notes on his signal horn.

NEWYORKER: Among Animals and Plants

Fyodorov played a long welcoming note on his horn to signal that the section was ready for the train to enter, and respectfully held his lantern out toward the engineer, his unknown friend, the only person who was aware of him at that moment, and who would be pleased that all was as it should be.

NEWYORKER: Among Animals and Plants

The fighting starts when a signal such as an air horn or whistle blows, and can last anywhere from a few minutes to a few hours.

BBC: Get rowdy at International Pillow Fight Day