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what; what sort of thing
everything; anything
what (on earth)?; what's the meaning of this ...?; what's this ... all about?
何事もなかったように彼は笑った。
He laughed as if nothing had happened.
向こうで何事か起きているらしい。
Something seems to be happening over there.
何事にも全力で取り組む姿勢が大切だ。
Give everything your full effort.