Ann and Susan each other since they were at school. A. knew B. had known C. have known D. would know
Ann and Susan ________ each other since they were at school.
A. knew
B. had known
C. have known
D. would know
Đáp án C
Giải thích: dùng thì hiện tại hoàn thành vì vế sau có since + quá khứ đơn
Dịch: Ann và Susan quen nhau từ khi họ còn đi học.