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to beat; to attack (an enemy); to do away with; to finish off
ヒーローが悪者をやっつけて町を救った。
The hero defeated the villains and saved the town.
試合で相手チームをやっつけて優勝した。
We beat the opposing team in the match and won the championship.
ゲームでボスをやっつけるのに苦労した。
I had trouble beating the boss in the game.