A student keeps using a native language while asking questions in the class when the course is taught in English I am assisting a statistics course in a university, and my main job in the course is conducting problem solving sessions. The course is taught in English, and students interact with me in English. However, there is one particular student who keeps using their native language. Whenever he does that, I reply in English, hoping that he would start using English. But he doesn't. 

I am sure that everybody does understand what he says because all the students are from the same part of the country. But I find it quite awkward. On the other hand, I feel that if I request him to use English, he might take it offensively, or he might not be able to express what he wants to say clearly. Should I simply ignore this particular case and move on? Or should I tell him somehow? If yes, what is the best way to convey this?
If you want a non-confrontation approach, simply repeat the question in English before answering it.

Hearing the translation may help the student in question see how to phrase their questions in English. It also give a polite hint that the question should have been asked in English.