saltpetre

例句：

1. 1. The ancient Chinese invented gunpowder to make fireworks.
   古代中国人发明了火药来制造烟花。
2. 2.Gunpowder was used in the 18th century for various purposes.
   火药在18世纪被用于各种目的。
3. 3.The explosion of gunpowder caused a great fire.
   火药爆炸引发了一场大火。