THEY FINISHED THEIR WORK ...A. BEFORE THREE HOURSB. SINCE THREE HO...

33. - 3500 CAU TRAC NGHIEM ON TAP AV THCS
3500 CAU TRAC NGHIEM ON TAP AV THCS

33. They finished their work ...

a. before three hours

b. since three hours

c. for three hours

d. three hours ago

--> d