Resposta:
a) I was travelling last year.
I) Was I travelling last year?
N) I wasn't travelling last year.
b) Your best friend is an excellent person.
I) Is your best friend an excellent person?
N) Your best friend isn't an excellent person.
c) Dr. Smith is working in this hospital.
I) Is Dr. Smith working in this hospital?
N) Dr. Smith isn't working in this hospital