“around the clock”的意思是“全天候，昼夜不断的”。around the clock指连续一整天。想象一下围着钟表转，一点都不停歇，岂不是夜以继日，不眠不休嘛。
around the clock使用例句
The restaurant is open around the clock.
A: Did you notice Kate? She looks not very well these days.
B: Oh yeah. She's been working around the clock for weeks.
We worked round the clock to finish the job.
We are studying around the clock when we are preparing for the final exam.
Hey. You've really been working around the clock lately. What's going on?
Doctors and nurses worked around the clock to help the people injured in the train crash.
This station broadcasts news around the clock.
Some stores stay open around the clock, while others do business for only a few hours a day.