why do not you turn off the lights before you leave the classroom?（改为同意句）— —you turn off the lights before —the classroom?

Question

why do not you turn off the lights before you leave the classroom?（改为同意句）
— —you turn off the lights before —the classroom?

Answer 1

_____Why __ don't ____you turn off the lights before____leaving_____ the classroom?
按理说此题应该是考察知识点Why don't you = Why not,注意Why not不能与you共存,可题目中又出现了you,所以不能用Why not,而只能把why do not 改为Why ,这也太……唉,现在的题呐~