הלכה על בכורות 36:53

One should not ask while standing, and one should not answer while standing. And some say that when one asks a matter of halacha, one needs to stand. (Tosafot, Chapter Pesulei HaMukdashin, in the name of the Yerushalmi) One should not ask from a high place, nor from a distance, nor from behind the elders. One should only ask about the topic at hand. One should only ask out of fear. One should not ask more than three halachot about the topic.