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

84. He started working as a teacher five years ago.

A. He has been working as a teacher for five years.

B. He has worked as a teacher since five years.

C. He is working as a teacher since five years.

D. He had been working as a teacher for five years