Two days ago you gave me a great book. I _______ reading it yet.

haven't finished is the best option to use here. Here is why: The sentence means that the action started in the past and continues to the present. We should use Present Perfect Tense. The correct choice is "haven't finished". don't finish is Present Simple and is not suitable. hasn't finished is used with singular subject and the subject here is I, so it's wrong. didn't finish is Past Simple and it doesn't express the meaning that reading is not finished yet. Answer: haven't finished