Therefore, it belongs to; Oxide.
Carbon monoxide is insoluble in water, so putting a pot of water indoors can't prevent poisoning. Not correct.
The books in the library are on fire. Although water can put out fires, it will corrode books. So the books in the library are on fire and cannot be put out with water. Not correct.
③ In physiological saline, water is the solvent. Correct.
Drinking hard water for a long time is harmful to your health. Not correct.
⑤ The atomized water in Shanghai Expo Park floats in the air to cool down. Correct.
So fill in: ③ ⑤.
(2) It is forbidden to discharge phosphorus-containing wastewater into rivers, to pile up domestic garbage at will along rivers and to discard waste batteries containing metals such as mercury and lead, which is beneficial to the protection of water resources;
It is unreasonable to resolutely put an end to the use of pesticides and fertilizers in farmland.
Therefore, fill in: ②.
(3) Watering flowers with washed rice can save water resources.
So, fill in: water the flowers with Taomi water.