The possessive form for the noun passerby is passerby's.
The noun 'passerby' is the singular form. The plural form is passersby.
Passerby
Passer-by.
The singular form is passerby; the plural for is passersby.
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