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quick; swift; nimble; agile
quick (understanding, judgement, etc.); alert; prompt
猫は素速い動きでテーブルの上の魚を奪った。
The cat snatched the fish from the table with a quick movement.
彼女の素速い対応に周囲は感心していた。
Everyone around her was impressed by her prompt response.
選手の切り返しは実に素速かった。
The player's change of direction was truly nimble.