evet - yes

Sen Türkçe mi öğreniyorsun? Are you learning Turkish?

Evet, Türkçe öğreniyorum.

Sen Türkçe öğreniyor musun? Are you learning Turkish?

Evet, öğreniyorum.

In the first question, as we tell the question word "mi" just after "Türkçe", we want to learn "especially" if that person is studying the Turkish Language. And in the second question, our emphasis is on "learning".