The baby is very mentally alert.

这孩子脑子很机灵。

《牛津词典》

To SUFFER from locked-in syndrome-to be mentally alert but physically paralysed-is one of the worst fates imaginable.

遭受闭锁综合症的折磨——精神状态机敏如常，但身体却瘫痪了——是可想象的最坏命运之一。

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The big question is whether they remain mentally alert because they engage in these activities, or whether they are able to engage in these activities because they are cognitively intact.

重要的问题在于，他们是否因为参加这类活动而保持了头脑的灵活，或是正因为他们拥有完整的认知能力，所以才有能力参与这类活动。

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He was heavily sedated and on a ventilator at Beth Israel Deaconess Hospital, but was "alert, mentally competent and lucid" during the brief initial court appearance at his bedside on Monday, U.S. Magistrate Judge Marianne Bowler found.

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Larger zoos employ behaviouralists to think up ways of keeping animals mentally alert.

ECONOMIST: From zoo cage to modern ark

We naturally trust people who listen, people who are mentally alert to the moment as it unfolds rather than thinking forward to their weekend or reflecting back on the missteps of a morning meeting.

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