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why; how; for what reason
「何故」 has another reading with different meanings.
why
なぜ遅れおくれたんですか。
Why were you late?
なぜそんなことを言っいったのか分からわからない。
I don't know why I said such a thing.
なぜこの道みちを選んえらんだのかと聞かきかれたら答えこたえに困るこまる。
If asked why I chose this path, I'd have trouble answering.