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why?; what for?
how?; by what means?
なんで今日はこんなに遅刻したの?
Why were you so late today?
なんでそんなことを言うのかわからない。
I don't understand why you'd say something like that.
なんで怒っているのか教えてほしい。
I want you to tell me why you're angry.