1.has been
-> Chia thì HTHT vì có since last year
2.has taught / graduated
-> HTHT + since + QKD
3. has driven/ knew
-> HTHT + since + QKD
4. haven't seen
-> Chia thì HTHT vì có since last Monday
5. don't live
6. have worked
7. hasn't smoken
-> Chia thì HTHT vì có for 5 years
8. have
-> How long + HTHT