15. When I stayed in a shared self-catered accommodation during studying
abroad, my roommate frequently offered: “_____”
(A) If you help me with the shopping, I will help you with your paper.
(B) If you helped me with the shopping, I would help you with your
paper.
(C) If you have helped me with the shopping, I would have helped you
with your paper.
(D) If you are helping me with the shopping, I will be helping you with
your paper.