The air we breathe is very important.
我们呼吸的空气非常重要。
Air is made of different gases.
空气由不同的气体组成。
One of these gases is oxygen.
其中一种气体是氧气。
Oxygen is the gas that people and animals need to live.
氧气是人类和动物生存所必需的气体。
When we breathe in, we take oxygen into our lungs.
当我们吸气时，氧气进入我们的肺部。
Our blood carries the oxygen to every part of our body.
我们的血液把氧气运送到身体的每个部分。
Without oxygen, our bodies cannot work properly.
没有氧气，我们的身体就无法正常运作。
Animals also need oxygen to stay alive.
动物也需要氧气才能生存。
Fish get oxygen from the water using their gills.
鱼类通过鳃从水中获取氧气。
Plants also need oxygen at night when they are not doing photosynthesis.
植物在晚上不进行光合作用时，也需要氧气。
Oxygen is made by plants through photosynthesis.
氧气是植物通过光合作用制造的。
That is why forests are important for clean air.
这就是为什么森林对清洁空气很重要。
The air around us is about 21% oxygen.
我们周围的空气大约有 21% 是氧气。
The rest of the air is mostly nitrogen and other gases.
空气的其余部分主要是氮气和其他气体。
If there is not enough oxygen, people and animals cannot survive.
如果氧气不足，人类和动物就无法生存。
That is why we cannot breathe in space or underwater without special equipment.
这就是为什么在太空或水下没有特殊设备时，我们无法呼吸。
In high places like mountains, there is less oxygen, so breathing is harder.
在像高山这样的高处，氧气较少，因此呼吸会更困难。
Clean air is important because pollution can make it hard to get enough oxygen.
清洁的空气很重要，因为污染会影响我们获取足够的氧气。
Now you know that oxygen in the air is essential for all living things!
现在你知道空气中的氧气对所有生命来说都是必不可少的了！
