Examples of Forming Plural Nouns:
1. Adding -s:
* Singular: cat Plural: cats
* Singular: book Plural: books
* Singular: table Plural: tables
* Singular: flower Plural: flowers
2. Adding -es:
* Singular: box Plural: boxes
* Singular: church Plural: churches
* Singular: brush Plural: brushes
* Singular: quiz Plural: quizzes
3. Changing -y to -ies:
* Singular: baby Plural: babies
* Singular: story Plural: stories
* Singular: fly Plural: flies
* Singular: puppy Plural: puppies
4. Irregular Plurals:
* Singular: child Plural: children
* Singular: man Plural: men
* Singular: woman Plural: women
* Singular: tooth Plural: teeth
* Singular: mouse Plural: mice
5. Unchanging Plurals:
* Singular: sheep Plural: sheep
* Singular: deer Plural: deer
* Singular: fish Plural: fish
6. Plurals of Foreign Words:
* Singular: alumnus Plural: alumni
* Singular: criterion Plural: criteria
* Singular: phenomenon Plural: phenomena
7. Plurals of Compound Nouns:
* Singular: mother-in-law Plural: mothers-in-law
* Singular: passerby Plural: passersby
* Singular: attorney general Plural: attorneys general
These are just a few examples. The formation of plural nouns can be complex, and there are many other rules and exceptions.