passers-by
The plural form of "passerby" is "passersby."
The plural form for the compound noun passer-by is passers-by.
The noun 'passerby' is the singular form. The plural form is passersby.
The singular form is passerby; the plural for is passersby.
passers-by
passersby
The possessive form for the noun passerby is passerby's.
The possessive form of the singular noun passerby is passerby's.example: That's a passerby's dog barking.
Passerby
"Passerby" can be spelled alternatively as "passer-by," so, conceivably, you would want to say "passers'-by," though you may just want to find another noun to convey the same meaning without the confusion.
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.