singular-plural

singular - plural

basis-bases
cactus – cacti

chef – chefs

chief – chiefs

city – cities

datum-data
gas –gasses

wife – wives

wolf – wolves

roof – roofs

belief – beliefs
medium-media

puppy – puppies

potato – potatoes

tomato – tomatoes

focus – foci

analysis – analyses

ellipsis – ellipses

phenomenon – phenomena

criterion – criteria

sheep – sheep

series – series

species – species

deer –deer

child – children

goose – geese

man – men

woman – women

tooth – teeth

foot – feet

mouse – mice

person – people
son in law-sons in law
brother in law-brothers in law
storey-storeys
story-stories
theory-theories
diary-diaries