She……………. well at school but that changed when she became friends with a different group of girls.
A. did
B. had done
C. had been doing
Câu trả lời là: C là đáp án đúng
Công thức nguyên hàm và tích phân
She……………. well at school but that changed when she became friends with a different group of girls.
A. did
B. had done
C. had been doing
Câu trả lời là: C là đáp án đúng