Look at the pattern: baby → babies · city → cities · story → stories. The y becomes ies. (But if a, e, i, o, or u comes right before the y, keep it: day → days. More on the next card.)
y → ies
baby → babies
city → cities
story → stories
Try it: Haffenville and Ghafwick are two ___. (cities / citys / city) Answer: cities — Close, the y changes here: city → cities (not "citys").
a, e, i, o, u + y → just -s
But when a, e, i, o, or u comes right before the y, keep the y and just add -s: key → keys · boy → boys · day → days.
key → keys
boy → boys
day → days
Try it: 1 day. Now seven ___. (days / daies / day) Answer: days — An a comes before the y in "day", so the y stays and you just add -s: days (not "daies").
Try it: One is a city, one is a boy. Two ___ and three ___. (cities … boys / citys … boies / cities … boies) Answer: cities … boys — Look at the letter before the y. City has t, which is not a, e, i, o or u, so the y becomes ies: cities. Boy has o, which is one of them, so the y stays: boys.
Try it: Look at the letter before the y. Two ___ and seven ___. (babies … days / babys … daies / babies … daies) Answer: babies … days — Baby has b before the y, and b is not a, e, i, o or u, so it becomes babies. Day has a before the y, so the y stays: days.
-f / -fe → -ves
Some common words ending in -f or -fe change to -ves. Learn these ones: knife → knives · leaf → leaves · wife → wives · life → lives. (A few add only -s, like roof → roofs.)
knife → knives
leaf → leaves
wife → wives
Try it: I need two ___ to cut the bread. (knives / knifes / knife) Answer: knives — Words ending in -fe change the f to v: knife → knives (not "knifes").
People: man, woman, child, person
These four change the word itself, not the ending: man → men · woman → women · child → children · person → people. Learn them by heart.
one man → two men
one woman → two women
one child → two children
one person → two people
Not "Three childs are here." — say "Three children are here.". These words never take -s. The word itself changes.
Try it: Two ___ are playing in Senville Park. (children / childs / childrens) Answer: children — "Child" does not follow the -s rule, its plural is the special form children (not "childs").
Try it: Many ___ come to Mosh Market on Saturday. (people / persons / peoples) Answer: people — If you added -s ("persons"), that is the regular ending, but this word does not take it: person → people. You will hear it every day.
Body: foot, tooth
Two body words change oo to ee: foot → feet · tooth → teeth. Same pattern, so learn them together.
one foot → two feet
one tooth → two teeth
Not "My foots are tired." — say "My feet are tired.". oo becomes ee. There is no -s.
Try it: Lars walks all morning. Now his ___ are tired. (feet / foots / feets) Answer: feet — "Foot" changes oo to ee: foot → feet. It never takes -s.
Try it: The dentist looks at my ___. (teeth / tooths / teeths) Answer: teeth — If you wrote "tooths", this word never takes -s. It works like foot: the oo becomes ee, so tooth → teeth.
Try it: Camila buys food for the party. Three ___ help her carry the bags. (women / womans / womens) Answer: women — If you added -s ("womans"), this word does not take it — the word itself changes: woman → women. Same family as man → men and child → children.