What is an example of the singular possessive case?
Singular possessive is always written with an apostrophe, and usually with an 's' after the apostrophe.
It can also be understood with the word "of" or "has/have".
When used with personal pronouns, it becomes "my/mine".
"I have a cat"
"Lewis has a dog"
"Lewis' dog" OR "Lewis's dog"
**Note: when a name/word ends with 's', you can either just put an apostrophe at the end with no 's' after it, or you can put an apostrophe, with an 's' after.
"The country has an army"
"The army of the country"
"The country's army"
"The woman's daughter"
"The daughter of the woman"
"The woman has a daughter"
This website has some really good explanations and examples: