In the scorching summer, although turning on the air conditioner indoors can reduce the temperature, closing doors and windows will cut off the air circulation. Therefore, keeping some "functionally complementary" flowers in the living room can serve as an "air filter". Most flowers carry out photosynthesis during the day, absorbing carbon dioxide and releasing oxygen, while at night they breathe, absorbing oxygen and releasing carbon dioxide. However, cacti, Sedum, and other similar plants do just the opposite. Keeping "functionally complementary" flowers in the same room can not only balance the content of oxygen and carbon dioxide in the room but also keep the indoor air fresh.