The word "necessary" is an adjective, and has no plural.
The noun form "necessity" has the plural form "necessities."
The plural of "necessary" is spelled "necessaries."
The plural of "bridge" is "bridges."
The plural of address is addresses.
The plural of "turkey" is "turkeys."
The plural form of him, her, or it is them. (objective pronouns)
The plural form is "cylinders."
Except where necessary for clarity, you would spell it "TVs." The plural form spelled out is "televisions."
The plural way to spell studio is studios.
The plural is "emeralds."
The plural of "bridge" is "bridges."
The plural is resources.
The plural is cherries.
The plural is hooves.
The plural is cantaloupes.
The plural is roses.
The plural of "instrument" is spelled "instruments."
The plural is a normal S plural, associates.
The plural of "race" is "races."