HÃY CHỌN MỘT ĐÁP ÁN ĐÚNG NHẤT (A, B, C HOẶC D) CHO MỖI CÂU SAU

28. - ON THI TRAC NGHIEM TIENG ANH 12BAM SAT
ON THI TRAC NGHIEM TIENG ANH 12BAM SAT

28. As I ________ my homework, he came yesterday afternoon.

A. did B. were doing C. am doing D. was doing