there isnt a plural form of a.
The plural form is challenges.
Arguments is in the plural form for the singular noun argument.
"Daffodils" is the plural of "daffodil."
The plural form is digits; the singular form is digit.
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."