Question 9: He _________ for over three hours when he finished the rep

Question 9: He _________ for over three hours when he finished the report.

• A. will have typed
• B. was typing
• C. has been typing
• D. had been typing

dùng quá khứ hoàn thành để diễn tả 1 hành động đã diễn ra trong 1 khoảng thời gian dài trong quá khứ.