He had very bad news last night, but he came to the office as cool as a cucumber this morning as if nothing had happened.

昨晚他发生了一件不幸的事情，但是今天来上班的时侯却表现的像黄瓜一样若无其事的样子。

youdao

He kept as cool as a cucumber as the newspaper reporters all shouted questions at him at once.

当新闻记者们一直同时向他提出问题时，他一直保持冷静沉着。

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

Jutting out of London's skyline in all its futuristic glory, the "Gherkin" building has managed in the last few years to embed itself in the city's psyche as an icon, an edifice that just looked as cool as a cucumber.

FORBES: Magazine Article

He was cool as a cucumber in his seersucker suit.

CNN: Mardi Gras 2006