二氧化碳 (èr yǎng huà tàn): carbon dioxide

Plants absorb carbon dioxide and release oxygen through photosynthesis, which is why forests are called the lungs of the Earth.

Scientists warn that continuously rising carbon dioxide levels in the atmosphere will lead to global warming, and all countries must reduce emissions.

In the laboratory, the student bubbled carbon dioxide into clear limewater, and the solution quickly turned cloudy, proving the presence of carbon dioxide.

Using a carbon dioxide extinguisher to put out oil fires is very effective, because it can cut off oxygen and rapidly lower the temperature.

During intense exercise, the human body produces more carbon dioxide, so the breathing rate increases to expel it from the body in time.