Plants are more than just pretty to look at. They give us (fruit), vegetables and food we eat. Some plants even provide materials for medicine or (build) things. But do you know plants can do something even more amazing? They can make our homes, schools and workplaces much (healthy).
We spend a large part of our day indoors. (lucky), the air inside buildings can often be full chemicals (化学物质) from many things around us. This poor air quality (质量) can make us (feel) sick, causing sore eyes and throats, and even making it hard for us (breathe). When the air inside buildings gets really bad, people even call them "sick buildings".
The good news is that plants are like nature's little (superhero). They have a magic power fighting against bad air. Plants breathe in carbon dioxide (CO2) and breathe out oxygen (O2) which we humans need to live. They can also add moisture to the air if it's too dry, making it (comfortable)for us to breathe.