Possessive 's
We usually use 's to say that something belongs to someone.
My brother's car(The car belongs to my brother.)
Sally's bicycle(The bicycle belongs to Sally.)
With a plural noun that ends in a plural s, we only put an apostrophe (') after the plural s to show that something belongs to those people.
the teacher's bag(We're talking about one teacher.)
the teachers' room(We're talking about a group of teachers.)
With an irregular plural noun, similar to singular nouns, we simply put an 's at the end of the irregular noun.
our children's books
men's clothes
As we can see from the examples above, we usually use 'swhen we're talking about people. When we're talking about things, we usually use the preposition "of".
the end of the book
the color of the wall
We use the question word "whose" to ask about possessions
A: Whose bicycle is that? / Whose is that bicycle?
B: It's Sally's bicycle.
A: Whose books are these? / Whose are these books?
B: They're my parents' books.
Exercises
Choose the correct form printed in italics.
1.It's my birthday's brother / brother's birthday.
It's my brother's birthday.
2.That's Jack's camera / camera's Jack.
That's Jack's camera.
3.My wife's car / car's wife is on the street.
My wife's car is on the street.
4.Who's / Whose laptop is this?
Whose laptop is this?
5.His parents's / parents' house is very big.
His parents' house is very big.
6.I like watching a TV show at the day's end / the end of the day.
I like watching a TV show at the end of the day.