Câu hỏi: Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
I saw an accident while I ________ my friend yesterday .
A. waited
B. had waited
C. was being waited
D. was waiting
I saw an accident while I ________ my friend yesterday .
A. waited
B. had waited
C. was being waited
D. was waiting
"When" dùng để diễn tả 1 hành động đang xảy ra 1 hành động khác xen vào
Thì quá khứ tiếp diễn .
Thì quá khứ tiếp diễn .
Đáp án D.