The present-tense verb in the sentence is "teach."
The reason for this is, while "will see," "learned," and "lived" are all verbs as well, "will see" is future-tense; as the word "will" implies that it hasn't happened yet and has yet to happen, while "learned" and "lived" are past-tense, as the "-ed" implies that it already has happened--as the speaker of the sentence has already lived in Paris (and perhaps does not any longer) and learned French while they lived there. "Teach" is implying that it is going to happen at this instance, as there is no "will" in front of it to imply future-tense, and no "-ed" at the end to imply past-tense.
I hope this helped !!
