E. In present simple questions, we use do/ does
E1. In past simple questions, we use did.
E2. But do not use do/ does/ did if who/ what etc. is the subject of the sentence.
F. Questions ending in prepositions are very common in English. After Who, Which or What we often have a preposition at the end of the sentence.
F1. the position of preposition in questions beginning Who/ What/ Which/ Where …?
F2. We can use preposition + whom in formal style.