Does a waiter work in a fire station?
No, he doesn't.
Does a secretary work in an office?
Yes, she does.
Does a teacher work in a school?
Yes, she does.
He works in a post office.
A mail carrier.
Does a barber work in a barber shop?
Yes, he does.
A police officer protect / protects people.
protects
She fixes people's teeth.
Dentist
He works in a hospital.
Doctor