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