coucou!
faut déjà savoir que avec for on précise la durée (two years, four weeks...)
et avec since on utilise si vous souhaitez parler d'un point précis dans le temp ( last year, 1997..)
donc:
A. I have been working as a dog sitter for three years.
B. She has been working as a cashier since last year.
C. He has given private lessons since 2016.
D. since I was twelve, I have wanted to be a vet.
E. She has thought of being a teacher for one week.
