In theory I'm on call day and night.

理论上，我不分昼夜随叫随到。

《柯林斯英汉双解大词典》

I'll be on call the night of the party.

在聚会的晚上我将随时听凭召唤。

《牛津词典》

Doctors work an average of 90 hours a week, while a few are on call for up to 120 hours.

医生们平均每周工作90个小时，而有些出诊长达120个小时。

《柯林斯英汉双解大词典》

And scientists are reporting this week on what they call the "indirect costs" of a virus-resistance gene in Cucurbita.

VOA: special.2009.10.27

- Well, just a moment ago, we did have -- -- and this time I'll use some chalk here -- a moment ago, we did have a picture depicting what was going on when you call the function.

好的，刚才，我们确实有-,这一次我将用一些粉笔-,刚才，我们有一张图描绘了当我们调用函数的时候,会发生什么事情。

哈佛公开课 - 计算机科学课程节选

So on Sundays, there's like an antique market. We call it bric-a-brac.

所以每个星期天，这里是古董市场。我们称之为古玩。

有各种不同的魅力 - SpeakingMax英语口语达人

James Eadie is the coordinating surgeon on-call one recent evening at Balad field hospital in Iraq.

NPR: 'Miracle Workers' Save Lives at Balad Field Hospital

It said the first fire engine will remain full-time, with on-call firefighters crewing the second engine.

BBC: MP calls for rethink on Taunton fire service cuts

Full-time washers are on-call five days a week from 9 a.m. to 5 p.m.

FORBES: Getting A Job Washing Cars Is Harder Than Getting Into Harvard