There are two accepted forms for possessive singular nouns ending in s:
Add an apostrophe (') after the existing s at the end of the word: Nicholas'
Add an apostrophe s ('s) after the existing s at the end of the word: Nicholas's
Examples:
Nicholas' graduation party is tonight.
Nicholas's graduation party is tonight.
The singular possessive form of "test" is "test's".
The singular possessive pronouns are "my," "mine," "your," "yours," "his," "her," and "its."
The singular possessive form of "classmate" is "classmate's."
Taco's is the singular possessive.
The singular possessive form of county is county's.
The singular possessive form of "test" is "test's".
The singular possessive pronouns are "my," "mine," "your," "yours," "his," "her," and "its."
The singular possessive of "ant" is "ant's" and the plural possessive is "ants'".
Museum is singular. Museum's is singular possessive. Museums is plural. Museums' is plural possessive.
The singular possessive form of "classmate" is "classmate's."
Taco's is the singular possessive.
The singular possessive of dish is dish's
The singular possessive is Martin's.
Buzz's is the singular possessive.
The singular possessive is fish's.
Grave's is the singular possessive.
The singular possessive is biker's; the plural possessive is bikers'.