The noun aptitude is an uncountable noun; amounts of aptitude is expressed as some aptitude, a little aptitude, great aptitude, etc.
The plural form is challenges.
there isnt a plural form of a.
management aptitude test
Sports & physical aptitude test
Arguments is in the plural form for the singular noun argument.
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
Bridges is the plural form of bridge.
The plural form of "is" is "are."
The plural form of "I" is "we."
The plural form of "was" is "were."
"Groceries" is the plural form of "grocery."
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
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 plural form is metres.
Trenches is the plural form.