The plural of the acronym CO would be COs.
(Some styles still endorse the use of the apostrophe, the plural being CO's)
The abbreviation (co.) for company would be (cos.) for companies.
Co děláš? - singular Co děláte? - plural or polite singular
Cos. is the plural, but more often used is the abbreviation for the word company instead which is Co.
The plural of "she" is "they", so the plural of "she had" is "they had".
The plural of 'this' is 'these' and the plural of 'that' is 'those'.
Isthmi is plural. There are actually two plural forms. I will list them from singular to plural. Isthmus - Singular Isthmi - Plural Isthmuses - Plural
The plural of rose is roses. The plural possessive is roses'.
The plural of 'bunch' is bunches.The plural of 'ant' is ants.The plural of 'batch' is batches.The plural of 'day' is days.The plural of 'chimney' is chimneys.The plural of 'tomato' is tomatoes.The plural of 'umbrella' is umbrellas.The plural of 'donkey' is donkeys.The plural of 'sky' is skies.The plural of 'foot' is feet.The plural of 'show' is shows.
The plural form of can is cans.
Knights is a plural. It is the plural for knight.
applied is does not have a plural but is apply it does have a plural.
The plural is a regular plural, attics.
The plural for the noun loss is losses; the plural possessive is losses'.