他黎明时分就起床。

He gets up at ___the ___crack ___of ___dawn.

从黎明到睡觉时间，市民们不得不呼吸来自各种来源的污染空气。

From ___the ___crack ___of ___dawn until bedtime, citizens have to breathe polluted air from various sources.

跑步者在黎明时分出发，以避开中午的炎热。

The runners set off at ___the ___crack ___of ___dawn to avoid the midday heat.