She always stays cool, calm and collected in a crisis.

她在危急关头总是很冷静镇定，处之泰然。

《牛津词典》

She has a reputation for being calm and cool-headed.

她以冷静沉着著称。

《柯林斯英汉双解大词典》

Or is he cool, calm, and calculating? Does he radiate irrational self-confidence and exude a certainty of excellence that this world has never seen?

或者他冷静，镇定，富于心机？或者他散发出不理性的自负，并且确信自己出类拔萃，世所未见。

youdao

You might say a person is as cool as a cucumber if he never seems to worry about anything and stays calm in a stressful situation.

VOA: special.2011.02.13

"His cool,calm and collectiveness is very Hawaiian,"

VOA: standard.2010.01.16

Great Britain skip David Murdoch is very cool and calm and mentally very strong and calls the game so well.

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Hamdan was cool and calm as he addressed the court, wearing a light-colored jacket, a white shirt and traditional white headdress.

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It is absolutely not the case that people who are "cool, calm and collected" at the time of the trauma are setting themselves up for later trouble.

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