They are firefighters. They aren't policemen.
They were firefighters. They weren't policemen.
You are bored.
You were bored.
He isn't busy.
He wasn't busy.
She isn't a doctor. She's a nurse.
She wasn't a doctor. She was a nurse.
I'm not hungry. I'm thirsty.
I wasn't hungry. I was thirsty.
You are a student.
You were a student.
History class isn't fun. It is boring.
History class wasn't fun. It was boring.
They are excited.
They were excited.
We are hot.
We were hot.
She is happy.
She was happy.
The party is fun.
The party was fun.
I am late for school.
I was late for school.