Gdy pytasz o inne częsci zdania - stosujesz inwersję lub operatory.
She is drinking milk.
What is she drinking?
I drink milk at 8 o'clock.
When do you drink milk?
She drank a lot of milk yesterday.
How much milk did she drink yesterday?
itd.
Uważaj - niekoniecznie "who" na początku zdania oznacza pytanie o podmiot
Who did you meet yesterday? - Kogo spotkałeś wczoraj?