Parks
The noun park's is the singular possessiveform.The plural form of the singular noun park is parks.The plural possessive form is parks'.
The spelling park's is the singularpossessive form; for example:The park's entrance is on Third Street.The plural form for the noun park is parks. The plural possessive form is parks'.
Cactus is Singular. Cacti is Plural. Examples: I saw a cactus at the national park. I saw cacti at the natural park. This is not correct: I saw a cacti at the national park.
The words was and were are not singular or plural, BUT... WAS is used after a singular noun, and WERE is used after a plural noun. Examples: The dog (a singular noun) WAS walking in the park today. The dogs (a plural noun) WERE walking in the park today. A helpful saying to remember; He WAS, they WERE.
Parks.
parked
Yes the word parks is a plural noun. The singular noun is park.
The word "ground" can be both singular and plural. Singular: "The ground is wet." Plural: "The grounds of the park are well-maintained."
ir al parque = (to) go to the park ve/id al parque = go to the park (singular, plural - informal) vaya/vayan al parque = go to the park (singular, plural - formal)
The possessive form of "park rangers" is "park rangers'." This indicates that something belongs to or is associated with the group of park rangers. In this case, the apostrophe comes after the plural noun "rangers" to show possession.
Valet, singularValets, plural
The nouns in the sentence are:orchestra, a singular, common noun (subject of the sentence).park, a singular, common noun (object of the preposition 'in')Sundays, a plural, proper noun (object of the preposition 'on')