I think you have asked me five or six questions since we have begun this exercise.
I think you have asked me five or six questions since we have begun this exercise.
A. I think
B. or
C. have begun
D. this
Đáp án C
Have begun -> beganCấu trúc: S + V (hiện tại hoàn thành) + since + S + V (quá khứ đơn)