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to notice; to realize; to realise; to become aware (of); to perceive; to sense; to suspect
to regain consciousness; to come to (one's senses); to come round
今日ようやく彼の態度の変化に気付いた。
I noticed his change.
病院で目を覚まして気が付く。
I came to in the hospital.
間違いに気付いて、すぐに直しました。
I noticed the mistake and corrected it immediately.