"What you gave me is really interesting."
When I say this kind of sentence, what I want to say is like below.
"I have one object. And it was given to me from you in the past. Now, I think it is really interesting."
That's why I use the past tense in the first verb 'give' and the present tense in the second verb 'be'.
But the textbooks in my country say that it is wrong because I use different tenses in one sentence. So is it really wrong? If it is, is there any way that I can describe two different time point in one sentence?