What is the covalent bond for CO?

The carbon monoxide molecule is correctly represented by a triple covalent bond between the carbon and oxygen atoms. One of the bonds is a coordinate covalent bond, a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.

Explanation:

Covalent bond or common bond is one of the types of chemical bonds. This connection arises from electronic participation. In fact, atoms that need to receive electrons to achieve stable electron arrangement (noble gas electron arrangement or octagonal arrangement) share electrons in their valence layer with other atoms. In this case, the transfer of electrons from one atom to another does not take place, but only a pair of electrons, called a bonded or shared electron pair, belongs to the nucleus of two atoms.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).