pyrotechnic signal

例句：

1. 1.The city held a grand fireworks display to celebrate the New Year's Eve.
   该市举办了一场盛大的焰火表演来庆祝新年前夕。
2. 2. The firemen used a pyrotechnic signal to alert the public of an emergency.
   消防员使用焰火信号来警告公众紧急情况。
3. 3.The children were thrilled by the pyrotechnic display at the fair.
   孩子们对嘉年华上的焰火表演感到兴奋。