smokeless flare

例句：

1. 1.They used a smokeless flare to signal their presence in the dark night.
   他们在黑暗的夜晚使用无烟火炬来发出他们的存在信号。
2. 2. The firefighters used a smokeless flare to warn the nearby residents of the danger.
   消防员们使用无烟火炬来警告附近的居民危险。
3. 3.The new invention of smokeless flares has greatly improved safety during outdoor activities.
   新型无烟火炬的发明大大提高了户外活动的安全性。