今天早上， 黄 老师和我们一起做一个实验。材料很简单一根短短的蜡烛、一个透明的玻璃杯还有一个打火机。老师先拿起火机“啪”的一声点燃了蜡烛，再小习翼翼地拿起玻璃杯轻轻地盖在蜡烛上面，渐渐地火苗熄灭了。大家都议论纷纷“为什么火会灭了呢？” 后来 老师告诉我们，原来蜡烛的燃烧需要空气中的氧气，当玻璃杯中的氧气耗完了，蜡烛就灭了。
今天我们又明白了一个道理：人呼吸需要氧气，燃烧也需要氧气。
Today we understand another truth: people need oxygen to breathe, and oxygen to burn.
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