The plural form of "do" is "do" and the plural form of "don't" is "don't." These words do not change in the plural form when used in a sentence.
The plural form of him, her, or it is them. (objective pronouns)
The plural form of "was" is "were."
The plural form of mouth is mouths. The plural form of month is months. The Mounth is a range of hills in Scotland and does not have a plural form.
The plural form of the demonstrative pronoun 'that' is those.
The singular form is septum; the plural form is septa.
Septa.
A single opening of your nose is known as a nostril, nostrils is the plural form. Your nostrils are two channels through the nose, separated by the septum.
Nasal septum
The vomer is the nasal septum.
Bridges is the plural form of bridge.
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
There is no plural form for the word, countries. This word itself is a plural.
"Groceries" is the plural form of "grocery."
The plural form of "meter" is "meters."
It has no plural form.
The plural form for the noun sergeant is sergeants; the plural possessive form is sergeants'.