sequence of tenses

[Will17]

Hello!

What is the right sequence of tenses for this sentence?

-Have you forgotten what I've taught you?

-Have you forgotten what I taught you?

-Did you forget what I've taught you?

-Did you forget what I taught you?

Thank you!

W

[Tdol]

It depends on various factors- has the tuition finished or is it ongoing? Are you asking at the time you became aware of their forgetting or afterwards?