Are they builders?
Yes, they are.
Who are they?
Waiters
Are they vets?
Yes, they are.
Who is this?
builder
Who is this?
teacher
Are they teachers?
No, they aren't.
Who is this?
waiter
Are they pupils?
No, they aren't.
Who are they?
builders
Who is this?
pupil
Who are they?
vets
Who is this?
vet
Are they pupils?
Yes, they are.
Are they waiters?
No, they aren't.