We use a noun with ’s with a singular noun to show possession:
我们用一个名词加“’s”表示所有者:

We are having a party at John’s house.

Michael drove his friend’s car.

We use s’ with a plural noun ending in -s:
也可以在复数名词后面加“s'”表示共同所有:

This is my parents’ house.

Those are ladies’ shoes.

But we use ’s with other plural nouns:
但是其他复数名词后面加“'s”表示共同所有:

These are men’s shoes.

Children’s clothes are very expensive.

We can use a possessive instead of a noun phrase to avoid repeating words:
使用名词的所有格做回答,而不是名词短语,可以避免重复。