强调句型 it is 还是it was?

题目

强调句型 it is 还是it was?
这个怎么用?
我也这么以为可是书上的句子是
It is from my grand parents that I learned a lot.

答案

书本上有问题.答案或者是 ：It is from my grand parents that I have learned a lot,或者是：It was from my grand parents that I learned a lot.