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》

See if you can rework your schedule and come up with practical ways to reduce the number of hours you're on call.

看看你能否修改你的时间表，想出切实可行的方法来减少你待命的时间。

《柯林斯英汉双解大词典》

Doctor Liu is on call at all times.

不论什么时候刘医生随叫随到。

youdao

For the next 12 hours, the medevac teams and machines will be on call to evacuate wounded troops from anywhere in eastern Afghanistan to Bagram's military-run trauma hospital.

VOA: standard.2010.04.27

I wonder have any of you reflected on, I don't want to call it shadow side, is not domesticated.

不知道你们有没有人想过这个问题，我不想说这是自然的阴暗面，无法驯化的一面。

普林斯顿公开课 - 人性课程节选

Do you have available to you what we call the hacker editions in more details on those in the courses syllabus?

你是否有黑客版套题,比教学大纲上的版本更详细？

哈佛公开课 - 计算机科学课程节选

Caregivers are often overwhelmed and being on call round-the-clock leaves their patience in tatters.

CNN: When Alzheimer's turns violent

There are no limits on call times, and the resulting sessions occasionally resemble protracted talk therapy.

NEWYORKER: Happy Feet

The growth of mobile phone use has had a dramatic impact on call handling.

BBC: Technology tackles bogus 999 calls