Here's why:

* Acidic oxides react with water to form acids. For example, sulfur dioxide (SO₂) reacts with water to form sulfurous acid (H₂SO₃).

* Basic oxides react with water to form bases. For example, calcium oxide (CaO) reacts with water to form calcium hydroxide (Ca(OH)₂).

* Neutral oxides do not react with water to form acids or bases. Carbon monoxide does not react with water in this way.

While CO can react with other substances like oxygen, it doesn't exhibit the typical behavior of acidic or basic oxides.