“…did you use to…?” The regular declarative form would be “you used to,” but turning it into a question involves inserting “do,” which takes the past tense marking (do → did) from “used,” so that "used becomes “use.” Native speakers should do all this automatically.
“…did you use to…?” The regular declarative form would be “you used to,” but turning it into a question involves inserting “do,” which takes the past tense marking (do → did) from “used,” so that "used becomes “use.” Native speakers should do all this automatically.