I am a Japanese undergraduate junior student who is thinking of applying to graduate programs in Mathematics in the U.S. and the biggest problem for me is the Letter of Recommendation. I am planning to ask a teacher of my English class for one of my LOR because my senior who went for a grad school(Engineering) in the U.S. did so. My intention is that she can prove that I have sufficient English skills to study in the U.S.
However, from what I have seen on the Internet, no one seemed to do so and all of LORs have to be from people in relevant fields. Is getting a LOR from an English teacher for Math Ph.D. program good or bad?