Additional info here: You can use this approach in teaching question-making.
Maria drew a picture on the wall last night.
Question about the subject:
1. Who drew a picture on the wall last night?
Questions Not about the subject: when. where, what etc.
1. What did Maria draw on the wall last night?
2. Where did Maria draw the picture last night?
3. When did Maria draw the picture on the wall?
4. What did Maria do last night?
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20 million People live in Norway.
about the subj:
How many people live in Norway. ( no need for aux verb.)
The red car is mine.
Which car is yours? (no need for aux verb, either)
Hope this helps!