- Can I ask you a question?
(질문을) 물어봐도 돼요?
I think you can just say 물어봐도 돼요?
- How was school?
- Did you finish your homework?
숙제가 다 끝났어요?
- What is the most natural way to say _______ in Korean?
________는 한국어로 말해 주세요
Targeted audience, Korean speaker. No need to mention anything about being 'natural'.
- I'm waiting for the bus
버스 기다리고 있어요
- I don't know how to answer that
그걸 대답할 줄 몰라요