At the crack of dawn, he would run up the slopes with his skis on, an unbelievably backbreaking activity.

在黎明时分，他会穿着滑雪板跑上斜坡。做这样一项非常耗费体力的运动让人难以置信。

youdao

A third group are known as crepuscular: they thrive in the low light of dawn and dusk and remain inactive at other hours.

第三组被称为黄昏组：他们在黎明和黄昏的微光中茁壮成长，而在其他时间则不活跃。

youdao

These days they were up at the crack of dawn.

这些天他们在破晓时就起床。

《柯林斯英汉双解大词典》

And we do. Cracking jokes,grins, Long past the crack of dawn Like"How long will you be up?"

VOA: special.2009.04.17

So I went by night and fought against it from the break of dawn until noon, taking it and slaying all 7000 men, boys, women and girls and maid servants, for I had devoted them to destruction for the god Ashtar Chemosh", referring to herem. It is likely that such claims are hyperbolic in Moab and it is likely they were hyperbolic in Israel.

我连夜赶路，与它战斗,从破晓到正午，拿下了它,屠杀了全部7000个长幼男人和女人，还有女仆，我奉献他们给阿斯塔基摩神，这便是祭祀，这些很有可能是摩押的假设,他们在以色列也很有可能是虚构的。

耶鲁公开课 - 旧约导论课程节选

Importantly, though, morning and dawn are also seen as moments of passion.

但重要的是黎明和早上,都可被视为激情的时刻。

耶鲁公开课 - 现代诗歌课程节选

At the crack of dawn, the dreaded wakeup call destroys any hope of a leisurely sleep-in.

CNN: ASIANOW - TIME Asia | Asia Buzz: What, No Coffee?

The working day began at 8am, the crack of dawn for investment bankers in those days.

ECONOMIST: Siegmund Warburg

We arrive at the crack of dawn, having been told that the runners will be training early.

BBC: Kenya's Olympic challenge