The conjugation "is" is the third person singular, present tense of "to be."
The third person plural, present tense, is "are" (they are).
The plural form for the noun form is forms.
Of doesn't have a plural form
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."
The plural form of the demonstrative pronoun 'that' is those.
The plural form for the noun sergeant is sergeants; the plural possessive form is sergeants'.
It has no plural form.
The plural form of rung is rungs.
The plural form of parenthesis is parentheses.
"Important" is an adjective. It does not have a plural form.
The plural form of "viola" is "violas."