2. Nouns ending in y with a consonant before it
change –y to –i and add –es.
Examples:
family- families army- armies
sky- skies grocery- groceries
3. Nouns ending in a consonant or single vowel
plus –f or –fe change to –v and add –es.
Examples:
scarf - scarves
shelf - shelves
knife - knives
half - halves
4. Nouns ending with two vowels plus –f add -s
chief - chiefs
reef - reefs
roof - roofs
Examples: